Bus bar link for battery cell interconnections in a battery module

ABSTRACT

A bus bar including a first end comprising a first material and a second end comprising a second material and a method of manufacture are provided. The first end is designed to be coupled to a terminal of a first battery cell of a battery module and includes a first collar disposed on the first end designed to receive and surround the terminal of the first battery cell of the battery module. The second end is designed to be coupled to a terminal of a second battery cell of the battery module and includes a second collar disposed on the second end designed to receive and surround the terminal of the second battery of the battery module. The first and second batteries of the battery module are adjacent to one another. Moreover, the bus bar includes a joint electrically and mechanically coupling the first end and the second end.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/230,827, filed on Mar. 31, 2014, entitled BUS BAR LINK FOR BATTERYCELL INTERCONNECTIONS IN A BATTERY MODULE, which claims priority fromand the benefit of U.S. Provisional Application Ser. No. 61/874,472,entitled “Battery Module System and Method”, filed Sep. 6, 2013, theentireties of both of which are hereby incorporated by reference intheir entireties for all purposes.

BACKGROUND

The present disclosure relates generally to the field of batteries andbattery modules. More specifically, the present disclosure relates tobattery modules that may be used in vehicular contexts, as well as otherenergy storage/expending applications.

This section is intended to introduce the reader to various aspects ofart that may be related to various aspects of the present disclosure,which are described and/or claimed below. This discussion is believed tobe helpful in providing the reader with background information tofacilitate a better understanding of the various aspects of the presentdisclosure. Accordingly, it should be understood that these statementsare to be read in this light, and not as admissions of prior art.

A vehicle that uses one or more battery systems for providing all or aportion of the motive power for the vehicle can be referred to as anxEV, where the term “xEV” is defined herein to include all of thefollowing vehicles, or any variations or combinations thereof, that useelectric power for all or a portion of their vehicular motive force. Aswill be appreciated by those skilled in the art, hybrid electricvehicles (HEVs) combine an internal combustion engine propulsion systemand a battery-powered electric propulsion system, such as 48 volt or 130volt systems. The term HEV may include any variation of a hybridelectric vehicle. For example, full hybrid systems (FHEVs) may providemotive and other electrical power to the vehicle using one or moreelectric motors, using only an internal combustion engine, or usingboth. In contrast, mild hybrid systems (MHEVs) disable the internalcombustion engine when the vehicle is idling and utilize a batterysystem to continue powering the air conditioning unit, radio, or otherelectronics, as well as to restart the engine when propulsion isdesired. The mild hybrid system may also apply some level of powerassist, during acceleration for example, to supplement the internalcombustion engine. Mild hybrids are typically 96V to 130V and recoverbraking energy through a belt or crank integrated starter generator.Further, a micro-hybrid electric vehicle (mHEV) also uses a “Stop-Start”system similar to the mild hybrids, but the micro-hybrid systems of amHEV may or may not supply power assist to the internal combustionengine and operates at a voltage below 60V. For the purposes of thepresent discussion, it should be noted that mHEVs typically do nottechnically use electric power provided directly to the crankshaft ortransmission for any portion of the motive force of the vehicle, but anmHEV may still be considered as an xEV since it does use electric powerto supplement a vehicle's power needs when the vehicle is idling withinternal combustion engine disabled and recovers braking energy throughan integrated starter generator. In addition, a plug-in electric vehicle(PEV) is any vehicle that can be charged from an external source ofelectricity, such as wall sockets, and the energy stored in therechargeable battery packs drives or contributes to drive the wheels.PEVs are a subcategory of electric vehicles that include all-electric orbattery electric vehicles (BEVs), plug-in hybrid electric vehicles(PHEVs), and electric vehicle conversions of hybrid electric vehiclesand conventional internal combustion engine vehicles.

xEVs as described above may provide a number of advantages as comparedto more traditional gas-powered vehicles using only internal combustionengines and traditional electrical systems, which are typically 12 voltsystems powered by a lead acid battery. For example, xEVs may producefewer undesirable emission products and may exhibit greater fuelefficiency as compared to traditional internal combustion vehicles and,in some cases, such xEVs may eliminate the use of gasoline entirely, asis the case of certain types of PHEVs.

As xEV technology continues to evolve, there is a need to provideimproved power sources (e.g., battery systems or modules) for suchvehicles. For example, it is desirable to increase the distance thatsuch vehicles may travel without the need to recharge the batteries.Additionally, it may also be desirable to improve the performance ofsuch batteries and to reduce the cost associated with the batterysystems.

SUMMARY

Certain embodiments commensurate in scope with the originally claimedsubject matter are summarized below. These embodiments are not intendedto limit the scope of the disclosure, but rather these embodiments areintended only to provide a brief summary of certain disclosedembodiments. Indeed, the present disclosure may encompass a variety offorms that may be similar to or different from the embodiments set forthbelow.

The present disclosure relates to batteries and battery modules. Morespecifically, the present disclosure relates to all electrochemical andelectrostatic energy storage technologies (e.g. ultracapacitors,nickel-zinc batteries, nickel-metal hydride batteries, and lithiumbatteries). Particular embodiments are directed to lithium ion batterycells that may be used in vehicular contexts (e.g., xEVs) as well asother energy storage/expending applications (e.g., energy storage for anelectrical grid).

Presently disclosed embodiments are directed to systems and methods forelectrically coupling battery cells in a battery module for use in xEVs.Existing battery systems typically use standard bus bars for coupling anumber of battery cells within battery modules. When used toelectrically couple battery cells having battery terminals made ofdifferent materials, additional components such as fasteners or adaptersare often used to facilitate the connection. These additional componentscan complicate an assembly of the battery module, increase electricalresistance between the battery along the bus bars, and add undesirablebulk to the battery module. Moreover, in systems where the bus bars arewelded to the terminals, the bus bars may be subject to improperplacement or misalignment when used to couple battery terminals made ofdifferent materials. It is now recognized that improved bus bars thatcan simplify installation onto battery terminals made of differingmaterials are desired.

Accordingly, the present embodiments are directed specifically to abattery module that includes a housing, a plurality of battery cellsdisposed in the housing, and a bus bar configured to electrically coupleadjacent battery cells of the plurality of battery cells. The bus barincludes a first end coupled to a first terminal of one of the pluralityof battery cells. In some embodiments, the first end and the firstterminal each include a first material. Also, the first end includes afirst collar disposed on a lower surface on the bus bar configured toreceive and surround the first terminal. The bus bar also includes asecond end coupled to a second terminal of an adjacent battery cell ofthe plurality of battery cells. The second end and the second terminaleach are formed from a second material. In some embodiments, the secondend includes a second collar disposed on the lower surface of the busbar configured to receive and surround the second terminal. The firstand second materials are different materials. Moreover, the bus barincludes a joint disposed between the first end and the second end. Thejoint mechanically and electrically couples the first end to the secondend.

Present embodiments also are directed to a bus bar that includes a firstend comprising a first material. The first end is designed to be coupledto a terminal of a first battery cell of a battery module. The bus baralso includes a first collar disposed on the first end and comprisingthe first material. In some embodiments, the first collar is designed toreceive and surround the terminal of the first battery cell of thebattery module. Additionally, the bus bar includes a second endcomprising a second material. The second end is designed to be coupledto a terminal of a second battery cell of the battery module. The firstand second batteries of the battery module are adjacent to one another.In some embodiments, the first and second batteries include prismaticcells with terminal posts extending upward from the prismatic cells. Thebus bar also includes a second collar disposed on the second end andcomprising the second material. The second collar is designed to receiveand surround the terminal of the second battery of the battery module.Moreover, the bus bar includes a joint electrically and mechanicallycoupling the first end and the second end. The joint is designed toprovide a gas tight seal between the first end and the second end.

The present disclosure also relates to a method of manufacture of abattery module. This method may, in certain embodiments, includedisposing a first battery cell and a second battery cell adjacent oneanother in a housing of the battery module. In some embodiments, thefirst battery cell includes a first terminal extending from the firstbattery cell. Also, the second battery cell includes a second terminalextending from the second battery cell adjacent the first terminal ofthe first battery cell. Furthermore, the first terminal comprises afirst material and the second terminal comprises a second materialdifferent from the first material. The method may also include disposinga bus bar over the first terminal and the second terminal such that thefirst terminal couples to a first end of the bus bar and the secondterminal couples to a second end of the bus bar. In some embodiments,the first end comprises the first material and the second end comprisesthe second material. Furthermore, the method may include surrounding thefirst terminal with a first collar formed in the first end of the busbar. Additionally, the method may include surrounding the secondterminal with a second collar formed in the second end of the bus bar.The method may also include welding the first end of the bus bar to thefirst terminal and the second end of the bus bar to the second terminal.

DRAWINGS

These and other features, aspects, and advantages of the presentdisclosure will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a perspective view of a vehicle (an xEV) having a batterysystem contributing all or a portion of the power for the vehicle, inaccordance with an embodiment of the present approach;

FIG. 2 is a cutaway schematic view of the xEV of FIG. 1 in the form of ahybrid electric vehicle (HEV), in accordance with an embodiment of thepresent approach;

FIG. 3 is a cutaway schematic view of the xEV of FIG. 1 in the form of amicrohybrid electric vehicle (mHEV), in accordance with an embodiment ofthe present approach;

FIG. 4 is a schematic view of the mHEV of FIG. 3 illustrating powerdistribution throughout the mHEV, in accordance with an embodiment ofthe present approach;

FIG. 5 is a perspective view of a battery module for use in the batterysystem of FIG. 1 , in accordance with an embodiment of the presentapproach;

FIG. 6 is an exploded perspective view of the battery module of FIG. 5 ,in accordance with an embodiment of the present approach;

FIG. 7 is a perspective view of a lower housing of the battery module ofFIG. 5 , in accordance with an embodiment of the present approach;

FIG. 8 is a side cutaway view of the lower housing of FIG. 7 , inaccordance with an embodiment of the present approach;

FIG. 9 is a top view of the lower housing of FIG. 7 , in accordance withan embodiment of the present approach;

FIG. 10 is a partial perspective view of the lower housing of FIG. 7illustrating heat fins on an outer surface of the lower housing, inaccordance with an embodiment of the present approach;

FIG. 11 is a cross sectional view of an interface between the lowerhousing and a cover of the battery module of FIG. 5 , in accordance withan embodiment of the present approach;

FIG. 12 is a perspective view of certain components of the batterymodule of FIG. 5 illustrating terminal posts of the battery module, inaccordance with an embodiment of the present approach;

FIG. 13 illustrates one of the terminal posts of FIG. 12 beingmanufactured via a cold-forming technique; in accordance with anembodiment of the present approach;

FIG. 14 is a perspective view of a terminal post in accordance with anembodiment of the present approach;

FIG. 15 is a perspective view of a terminal post in accordance with anembodiment of the present approach;

FIG. 16 is a perspective view of a shunt mounted directly onto a printedcircuit board (PCB) of the battery module of FIG. 12 , in accordancewith an embodiment of the present approach;

FIG. 17 is a perspective view of a high current interconnect assemblyfor use on a PCB of the battery module of FIG. 12 in accordance with anembodiment of the present approach;

FIG. 18 is a side cutaway view of the high current interconnect assemblyof FIG. 17 , in accordance with an embodiment of the present approach;

FIG. 19 is a current flow diagram of the high current interconnectassembly of FIG. 18 , in accordance with an embodiment of the presentapproach;

FIG. 20 is a perspective view of bus bars, a bladed fuse assembly, andother high current components coupled to one another and to the PCB viathe high current interconnect assembly of FIG. 17 , in accordance withan embodiment of the present approach;

FIG. 21 is an exploded perspective view of the high current components,PCB, and high current interconnects of FIG. 20 , in accordance with anembodiment of the present approach;

FIG. 22 is a perspective view of the high current interconnect assemblyof FIG. 17 mounted on the PCB, in accordance with an embodiment of thepresent approach;

FIG. 23 is a diagrammatical representation of the battery system of FIG.1 coupled to electronic vehicle components via a direct current (DC)bus, in accordance with an embodiment of the present approach;

FIG. 24 is a diagrammatical representation of a pre-charge circuit thatmay be implemented via hardware on the PCB of FIG. 12 , in accordancewith an embodiment of the present approach;

FIG. 25 is a process flow diagram of the method of pre-charging the busbars of FIG. 20 , in accordance with an embodiment of the presentapproach;

FIG. 26 is a diagrammatical representation of a contactor relay controlcircuit that may be implemented via hardware on the PCB of FIG. 12 , inaccordance with an embodiment of the present approach;

FIG. 27 is a plot illustrating a current level measured as a function oftime in the contactor relay control circuit of FIG. 26 , in accordancewith an embodiment of the present approach;

FIG. 28 is a process flow diagram of a method of controlling a contactorrelay, in accordance with an embodiment of the present approach;

FIG. 29 is a side view of the bladed fuse assembly of FIG. 20 , inaccordance with an embodiment of the present approach;

FIG. 30 is a side view of the bladed fuse assembly of FIG. 20 coupled tothe PCB, in accordance with an embodiment of the present approach;

FIG. 31 is a perspective view of components of the battery module ofFIG. 12 illustrating bus bar cell interconnect assemblies within thebattery module, in accordance with an embodiment of the presentapproach;

FIG. 32 is a perspective view of a voltage sense connection tab, inaccordance with an embodiment of the present approach;

FIG. 33 is a perspective view of a voltage sense connection tab, inaccordance with an embodiment of the present approach;

FIG. 34 is an exploded perspective view of the bus bar cell interconnectassembly of FIG. 31 for electrically coupling battery cells, inaccordance with an embodiment of the present approach;

FIG. 35 is a front view of a hair-pin shaped bus bar for use in the busbar cell interconnect assembly of FIG. 31 , in accordance with anembodiment of the present approach;

FIG. 36 is a front view of a link bus bar for use in the battery cellinterconnect assembly of FIG. 31 , in accordance with an embodiment ofthe present approach;

FIG. 37 is a perspective view of an upper portion of a bus bar for usein the battery cell interconnect assembly of FIG. 31 , in accordancewith an embodiment of the present approach;

FIG. 38 is a perspective view of a lower portion of a bus bar for use inthe battery cell interconnect assembly of FIG. 31 , in accordance withan embodiment of the present approach;

FIG. 39 is a perspective view of the bus bar of FIGS. 37 and 38electrically coupling battery cells, in accordance with an embodiment ofthe present approach;

FIG. 40 is a top view of a lid for holding a PCB and temperature sensorsof the battery module of FIG. 6 , in accordance with an embodiment ofthe present approach;

FIG. 41 is a side cutaway view of the lid of FIG. 40 taken along line41-41 holding down battery cells of the battery module, in accordancewith an embodiment of the present approach;

FIG. 42 is a side cutaway view of a portion of the lid in FIG. 41holding down a battery cell of the battery module, in accordance with anembodiment of the present approach;

FIG. 43 is a perspective cutaway view of the lid of FIG. 40 taken alongline 41-41 with a vent chamber, in accordance with an embodiment of thepresent approach;

FIG. 44 is a bottom view of the lid of FIG. 40 with a vent chamber, inaccordance with an embodiment of the present approach;

FIG. 45 is a side cutaway view of the lid of FIG. 40 with a ventchamber, in accordance with an embodiment of the present approach;

FIG. 46 is a schematic perspective view of the battery module of FIG. 5having a vent discharge aperture in a side wall of the battery module,in accordance with an embodiment of the present approach;

FIG. 47 is a schematic perspective view of the battery module of FIG. 5having a vent discharge chimney extending out of the battery module, inaccordance with an embodiment of the present approach;

FIG. 48 is a perspective view of the battery module of FIG. 5 having afitting extending out of the battery module, in accordance with anembodiment of the present approach;

FIG. 49 is an exploded perspective view of the battery module of FIG. 5, in accordance with an embodiment of the present approach;

FIG. 50 is a process flow diagram of a method of assembling the batterymodule of FIG. 49 , in accordance with an embodiment of the presentapproach;

FIG. 51 is a perspective schematic view of layers of the PCB of FIG. 49, in accordance with an embodiment of the present approach; and

FIG. 52 is a top view of components of the battery module of FIG. 5illustrating positions where welds can be made during assembly of thebattery module, in accordance with an embodiment of the presentapproach.

DETAILED DESCRIPTION

It should be noted that terms such as “above”, “below”, “on top of”, and“beneath” may be used to indicate relative positions for elements (e.g.,layered components of the power and battery assemblies described below)and are not limiting embodiments to either of a horizontal or verticalstack orientation. Further, it should be noted that terms such as“above”, “below”, “proximate”, or “near” are intended to indicate therelative positions of two components or layers that may or may not be indirect contact with one another. Additionally, geometric references arenot intended to be strictly limiting.

As discussed above, there are several different types of xEVs. Althoughsome vehicle manufacturers produce only xEVs and, thus, can design thevehicle from scratch as an xEV, most vehicle manufacturers produceprimarily traditional internal combustion vehicles. Thus, when one ofthese manufacturers also desires to produce an xEV, it often utilizesone of its traditional vehicle platforms as a starting point. As can beappreciated, when a vehicle has been initially designed to use atraditional electrical system powered by a single lead acid battery andto utilize only an internal combustion engine for motive power,converting such a vehicle into its HEV version can pose many packagingproblems. For example, a FHEV uses not only these traditionalcomponents, but one or more electric motors must be added along withother associated components. As another example, a mHEV also uses notonly these traditional components, but a higher voltage battery (e.g., a48V lithium ion battery module) must be placed in the vehicle inaddition to the 12V lead acid battery along with other components suchas a belt integrated starter-generator, sometimes referred to as a beltalternator starter (BAS) as described in further detail below. Hence, ifa battery system can be designed to reduce such packaging problems, itwould make the conversion of a traditional vehicle platform into an xEVless costly and more efficient.

The battery systems described herein may be used to provide power to anumber of different types of xEVs as well as other energy storageapplications (e.g., electrical grid power storage systems). Such batterysystems may include one or more battery modules, each battery modulehaving a number of battery cells (e.g., lithium ion electrochemicalcells) arranged to provide particular voltages and/or currents useful topower, for example, one or more components of an xEV.

Present embodiments also include physical battery module features,assembly components, manufacturing and assembling techniques, and soforth, that facilitate providing disclosed battery modules and systemsthat have a desired form factor (e.g., dimensions approximatelycorresponding to or smaller than a traditional lead acid battery).Further, as set forth in detail below, the disclosed battery moduleembodiments include a lower housing configured to receive battery cellsof the battery module. In addition, the disclosed battery moduleembodiments include a lid assembly, a PCB assembly, battery terminalposts extending from the battery module, and a cover. Each of theseassemblies may include features that facilitate relatively easy assemblyof the battery module, lowered cost of assembling the battery module,longer life of the battery module, and reduced packaging of the batterymodule. These features are discussed in further detail below.

With the foregoing in mind, FIG. 1 is a perspective view of an xEV 10 inthe form of an automobile (e.g., a car) having a battery system 20 inaccordance with present embodiments for providing all or a portion ofthe power (e.g., electrical power and/or motive power) for the vehicle10, as described above. Although the xEV 10 may be any of the types ofxEVs described above, by specific example, the xEV 10 may be a mHEV,including an internal combustion engine equipped with a microhybridsystem which includes a start-stop system that may utilize the batterysystem 20 to power at least one or more accessories (e.g., AC, lights,consoles, etc.), as well as the ignition of the internal combustionengine, during start-stop cycles.

Further, although the xEV 10 is illustrated as a car in FIG. 1 , thetype of vehicle may differ in other embodiments, all of which areintended to fall within the scope of the present disclosure. Forexample, the xEV 10 may be representative of a vehicle including atruck, bus, industrial vehicle, motorcycle, recreational vehicle, boat,or any other type of vehicle that may benefit from the use of electricpower. Additionally, while the battery system 20 is illustrated in FIG.1 as being positioned in the trunk or rear of the vehicle, according toother embodiments, the location of the battery system 20 may differ. Forexample, the position of the battery system 20 may be selected based onthe available space within a vehicle, the desired weight balance of thevehicle, the location of other components used with the battery system20 (e.g., battery management systems, vents or cooling devices, etc.),and a variety of other considerations.

FIG. 2 illustrates a cutaway schematic view of an embodiment of the xEV10 of FIG. 1 , provided in the form of an HEV having the battery system20, which includes one or more battery modules 22. In particular, thebattery system 20 illustrated in FIG. 2 is disposed toward the rear ofthe vehicle 10 proximate a fuel tank 12. In other embodiments, thebattery system 20 may be provided immediately adjacent the fuel tank 12,provided in a separate compartment in the rear of the vehicle 10 (e.g.,a trunk), or provided in another suitable location in the xEV 10.Further, as illustrated in FIG. 2 , an internal combustion engine 14 maybe provided for times when the xEV 10 utilizes gasoline power to propelthe vehicle 10. The vehicle 10 also includes an electric motor 16, apower split device 17, and a generator 18 as part of the drive system.

The xEV 10 illustrated in FIG. 2 may be powered or driven by the batterysystem 20 alone, by the combustion engine 14 alone, or by both thebattery system 20 and the engine 14. It should be noted that, in otherembodiments of the present approach, other types of vehicles andconfigurations for the vehicle drive system may be utilized, and thatthe schematic illustration of FIG. 2 should not be considered to limitthe scope of the subject matter described in the present application.According to various embodiments, the size, shape, and location of thebattery system 20, the type of vehicle, the type of xEV technology, andthe battery chemistry, among other features, may differ from those shownor described.

The battery system 20 may generally include one or more battery modules22, each having a plurality of battery cells (e.g., lithium ionelectrochemical cells), which are discussed in greater detail below. Thebattery system 20 may include features or components for connecting themultiple battery modules 22 to each other and/or to other components ofthe vehicle electrical system. For example, the battery system 20 mayinclude features that are responsible for monitoring and controlling theelectrical and thermal performance of the one or more battery modules22.

FIG. 3 illustrates a cutaway schematic view of another embodiment of thexEV 10 of FIG. 1 , provided in the form of a mHEV 10 having the batterysystem 20. Such a battery system 20 may be placed in a location in themHEV 10 that would have housed a traditional battery prior to conversionto an mHEV. For example, as illustrated in FIG. 3 , the mHEV 10 mayinclude the battery system 20A positioned similarly to a lead-acidbattery of a typical combustion-engine vehicle (e.g., under the hood ofthe vehicle 10). By further example, in certain embodiments, the mHEV 10may include the battery system 20B positioned near a center of mass ofthe mHEV 10, such as below the driver or passenger seat. By stillfurther example, in certain embodiments, the mHEV 10 may include thebattery system 20C positioned below the rear passenger seat or near thetrunk of the vehicle. It should be appreciated that, in certainembodiments, positioning a battery system 20 (e.g., battery system 20Bor 20C) in or about the interior of the vehicle may enable the use ofair from the interior of the vehicle to cool the battery system 20(e.g., using a forced-air cooling design).

FIG. 4 is a schematic view of an embodiment of the mHEV 10 of FIG. 3having an embodiment of the battery system 20 disposed under the hood ofthe vehicle 10. As previously noted and as discussed in detail below,the battery system 20 may include a battery module 22 having dimensionscomparable to those of a typical lead-acid battery to limit or eliminatemodifications to the mHEV 10 design to accommodate the battery system20. The battery module 22 illustrated in FIG. 4 is a two-terminalbattery that is capable of providing approximately a 48V output. Forexample, a first terminal 24 may provide a ground connection, and asecond terminal 26 may provide a 48V output. However, it should be notedthat other embodiments of the battery module 22 described herein may becapable of storing and outputting power at a different voltage. Thebattery system 20 may include a DC-DC converter 28 for converting theoutput of the battery module 22 to a lower voltage (e.g., 12V). Asillustrated, the 48V output of the battery module 22 may be coupled to abelt alternator starter (BAS) 29, which may be used to start an internalcombustion engine 33 during start-stop cycle, and the 12 V output of theDC-DC converter 28 may be coupled to a traditional ignition system(e.g., starter motor 30) to start the internal combustion engine 33during instances when the BAS 29 is not used to do so. It should also beunderstood that the BAS 29 may also capture energy from a regenerativebraking system or the like (not shown) to recharge the battery module22.

It should be appreciated that the 48 V and 12 V outputs of the batterysystem 20 may also be provided to other components of the mHEV 10.Examples of components that may utilize the 48 V output in accordancewith present embodiments include radiator cooling fans, climate controlfans, electric power steering systems, active suspension systems,electric air-conditioning systems, auto park systems, cooled seats,electric oil pumps, electric super/turbochargers, electric water pumps,heated seats, heated windscreen/defrosters, and engine ignitions.Examples of components that may utilize the 12 V output from the DC-DCconverter 28 in accordance with present embodiments include window liftmotors, vanity lights, tire pressure monitoring systems, sunroof motorcontrols, power seats, alarm systems, infotainment online features,navigation features, lane departure warning systems, electric parkingbrakes, and external lights. The examples set forth above are notexhaustive and there may be overlap between the listed examples. Indeed,in some embodiments, features listed above as being associated with a 48V load may utilize the 12 V output instead and vice versa.

In the illustrated embodiment, the 48 V output of the battery module 22may be used to power one or more accessories of the mHEV 10. Forexample, as illustrated in FIG. 4 , the 48 V output of the batterymodule 22 may be coupled to a heating, ventilation, and air conditioning(HVAC) system 32 (e.g., including compressors, heating coils, fans,pumps, and so forth) of the mHEV 10 to enable the driver to control thetemperature of the interior of the mHEV 10 during operation of thevehicle. This is particularly important in an mHEV 10 during idleperiods when the internal combustion engine 33 is stopped and, thus, notproviding any electrical power via engine charging. As also illustratedin FIG. 4 , the 48 V output of the battery module 22 may be coupled tothe vehicle console 34, which may include entertainment systems (e.g.,radio, CD/DVD players, viewing screens, etc.), warning lights andindicators, controls for operating the mHEV 10, and so forth. Hence, itshould be appreciated that the 48 V output may, in certain situations,provide a more efficient voltage at which to operate the accessories ofthe mHEV 10 (e.g., compared to 12 V), especially when the internalcombustion engine 33 is stopped (e.g., during start-stop cycles). Itshould also be appreciated that, in certain embodiments, the 48 V outputof the battery module 22 may also be provided to any other suitablecomponents and/or accessories (e.g., lights, switches, door locks,window motors, windshield wipers, and so forth) of the mHEV 10.

Also, the mHEV 10 illustrated in FIG. 4 includes a vehicle controlmodule (VCM) 36 that may control one or more operational parameters ofthe various components of the vehicle 10, and the VCM 36 may include atleast one memory and at least one processor programmed to perform suchtasks. Like other components of the mHEV 10, the battery module 22 maybe coupled to the VCM 36 via one or more communication lines 38, suchthat the VCM 36 may receive input from the battery module 22, and morespecifically, a battery control module (BCM) of the battery module 22.For example, the VCM 36 may receive input from the battery module 22regarding various parameters, such as state of charge and temperature,and the VCM 36 may use these inputs to determine when to charge and/ordischarge the battery module 22, when to discontinue charging thebattery module 22, when to start and stop the internal combustion engine33 of the mHEV 10, whether to use the BAS 29 or the starter 30, and soforth.

Turning to FIG. 5 , present embodiments include the battery module 22,which may be considered generally representative of a battery modulethat is a non-lead acid battery (e.g., a battery module includingultracapacitors, nickel-zinc batteries, nickel-metal hydride batteries,and lithium batteries). In particular, the battery module 22 illustratedin FIG. 5 is a lithium ion battery module. Further, the battery module22 may include certain features, described in detail below, thatfacilitate the relatively easy and cost efficient manufacture of thebattery module 22. Additionally, the battery module 22 may includefeatures that enable a relatively small packaging of the battery module22, such that the battery module 22 may conform to an overall geometryor dimensions that are comparable to, or smaller than, the dimensions ofa lead-acid battery.

In the illustrated embodiment, the battery module 22 includes a lowerhousing 50 and a cover 52 that are coupled together to form an enclosureof the battery module 22. As described in detail below, this enclosuremay hold a number of prismatic battery cells, bus bars, printed circuitboards, and other equipment used to provide store and provide power at adesired voltage output. The battery terminals 24 and 26 extend out ofthe enclosed battery module 22 for coupling of an external load to thebattery module 22.

FIG. 6 is an exploded perspective view of the battery module 22 of FIG.5 . As illustrated, the battery module 22 may include, among otherthings, the lower housing 50, battery cells 54 disposed in the lowerhousing 50, a lid assembly 56, a printed circuit board (PCB) assembly58, battery terminals 24 and 26, and the cover 52. The lower housing 50and the cover 52 form an outer enclosure for the battery module 22, andthe battery cells 54, the lid assembly 56, and the PCB assembly 58 areheld within this enclosure. The battery terminals 24 and 26 areconfigured to protrude out of the enclosure formed by the lower housing50 and the cover 52, in order to facilitate attachment of an outsideelectric load to the battery module 22. Each of the illustrated sections(e.g., lower housing 50, lid assembly 56, PCB assembly 58, terminals 24and 26, and cover 52) include features, discussed in detail below, thatfacilitate the efficient assembly of a relatively compact battery module22.

It should be noted that, in the illustrated embodiment, the batterymodule 22 includes thirteen individual battery cells 54. As illustrated,the battery cells 54 may be arranged in a face-to-face, or stacked,orientation relative to each other. As discussed in detail below, thesebattery cells 54 may be coupled in series within the battery module 22to provide a desired voltage output. For example, to output a desiredvoltage of approximately 48V, each of the thirteen battery cells 54 maybe configured to provide a voltage within a range of approximately 3.5Vto 3.9V. Although the illustrated embodiment includes thirteen suchbattery cells 54, the battery module 22 may include any number ofindividual battery cells 54 coupled together in series, parallel, or acombination thereof, to provide the desired voltage output.

Having now generally introduced the features (e.g., lower housing 50,battery cells 54, lid assembly 56, PCB assembly, and cover 52) withinthe presently disclosed battery module 22, a more detailed discussion ofthese features will be provided. To facilitate discussion of the batterymodule 22 and the various assemblies and components thereof, an X axis60 is defined as extending through a width of the battery module 22, a Yaxis 62 is defined as extending through a length of the battery module22, and a Z axis 64 is defined as extending through a height of thebattery module 22.

Enclosure for Holding Battery Cells of a Lithium Ion Battery Module

FIG. 7 illustrates the lower housing 50 that may be used to hold thebattery cells 54 of the battery module 22. As mentioned above, thebattery module 22 may be a lithium ion battery with a number ofindividual lithium ion battery cells (e.g., battery cells 54) foroutputting a desired voltage from the battery module 22. The illustratedlower housing 50, in conjunction with other components of the batterymodule 22 (e.g., cover 52) is configured to hold and secure a number ofprismatic battery cells 54 in a face-to-face arrangement. As discussedin detail below, the lower housing 50 may include a number of featuresthat facilitate effective positioning, expansion force management,cooling, and overall enclosure of the battery cells 54. The lowerhousing 50 may be injection molded into a single piece having one ormore of the features described below. The lower housing 50 may beconstructed from any desirable materials, including, for example,glass-filled nylon or plastic.

In the illustrated embodiment, the lower housing 50 includes slots 70defined by ribs 72 (e.g., partitions) along an interior edge (e.g.,interior wall) of the lower housing 50. These slots 70 are designed toreceive and hold the prismatic battery cells 54 within the batterymodule 22. Although the ribs 72 are only visible on one interior wall 74of the lower housing 50 in FIG. 7 , another row of ribs 72 may bepresent along an opposing interior wall 76 of the lower housing 50, inorder to maintain the battery cells 54 in alignment relative to eachother, the lower housing 50, and other components of the battery module22. The ribs 72 (e.g., partitions) of the interior wall 74 may alignwith the ribs 72 (e.g., partitions) of the opposing interior wall 76.

FIG. 8 is a side view of the lower housing 50 showing the ribs 72 (e.g.,partitions) formed in the interior wall 74. The ribs 72 aresubstantially equally spaced relative to each other and designed to holdone prismatic battery cell 54 within each slot 70 formed betweenadjacent ribs 72. The ribs 72 may maintain the battery cells 54 in aposition spaced slightly apart from each other. This allows the batterycells 54 to swell and change dimensions without putting an undesirablestrain on the lower housing 50. That is, the ribs 72 are configured tohold the battery cells 54 therebetween in such a way that the batterycells 54 are restrained within the battery module 22 and are alsoallowed to expand due to temperature increases within the battery module22.

In traditional battery modules that utilize multiple prismatic batterycells, the battery cells are often clamped or otherwise bound togetherand then placed in an enclosure. As temperatures increase and each ofthe battery cells expands, the accumulated expansion force from all ofthe battery cells may be transferred to the structure that is holdingthem. However, the presently disclosed lower housing 50 features theribs 72, which allow each battery cell 54 to expand separately againstthe ribs 72, without applying an accumulated expansion force to each ofthe opposing ends of the lower housing 50. Decreasing this force on thelower housing 50 may allow a more compact packaging of the batterymodule 22 than would be available with traditional designs where thebattery cells are held together tightly.

In the illustrated embodiment, the ribs 72 are wider along a bottomportion 78 of the lower housing 50 than at a top portion 80 of the lowerhousing 50. That is, the ribs 72 extend further in the direction of theY axis 62 at the bottom portion 78 than they do at the top portion 80,as illustrated by a lower width dimension 82 of one of the ribs 72 withrespect to an upper width dimension 84 of the rib 72. This widening(e.g., reverse tapering) of the ribs 72 toward the bottom portion 78facilitates a narrowing of the slots 70 used to hold the battery cells54. This dimensioning of the ribs 72 may result in the battery cells 54being held more tightly at the bottom portion 78 of the lower housing 50than at the top portion 80.

The widening ribs 72 may facilitate relatively easy assembly of thebattery module 22. For example, the larger openings of the slots 70 atthe top portion 80 act as a lead-in for the battery cells 54 to assistin placement of the battery cells 54 into corresponding slots 70. Thewidening ribs 72 may accommodate tolerances inherent withinpick-and-place machinery used to lower the battery cells 54 into theslots 70 during assembly. In addition, the widening ribs 72 may enablemovement of the battery cells 54 near the top portion 80 so that thebattery cells 54 can be aligned with and welded to other componentswithin the battery module 22. The flexibility of movement of the batterycells 54 within the slots 70 may facilitate a simplified assemblyprocess while ensuring the battery cells 54 are held in place within thebattery module 22.

Additionally, the ribs 72 (e.g., partitions) may taper inwards withrespect to their thickness as they extend outwards (e.g., in directionx) from the interior walls 74, 76. In other words, the ribs 72 may taperinwards such that each of the ribs 72 forms a V-shaped cross sectionwhen observed from a top of the lower housing 50. For example, theV-shaped cross section of one of the ribs 72 may taper inwards at angle48, as shown in FIG. 9 . The angle 78 may fall within a range ofapproximately 30 and 50 degrees, 35 and 47 degrees, 40 and 44 degrees,or 41 and 43 degrees. In some embodiments, the taper may culminate intoan edge of each of the ribs 72.

The ribs 72 may be dimensioned such that there is a space between eachof the battery cells 54 when the battery cells 54 are aligned within theslots 70. For example, at the thickest part of the ribs (e.g., at thebottom portion 78), the ribs 72 may be positioned apart from each othera distance 80, where distance 80 may be in a range of approximately 10to 20 millimeters (mm), 11 to 18 mm, 12 to 16 mm, or 13 to 15 mm.Further, at the thickest part of the ribs 72 (e.g., at the bottomportion 78), a portion of the ribs 72 extend in a direction of the Xaxis 60 to a position between the battery cells 54 in the slots 70. Thisextended portion of each rib 72 may be approximately 1 mm in width insome embodiments. This may be wide enough to accommodate swelling andexpansion of the battery cells 54 within the slots 70, while keeping thebattery cells 54 anchored relative to each other within the batterymodule 22. The additional space between the battery cells 54 may reducean amount of expansion force that is transferred to the lower housing 50from the expanding battery cells 54. Because the force on the lowerhousing 50 is lessened, the lower housing 50 does not have to be able towithstand as much force as it would if the battery module 22 includedbattery cells 54 held in direct contact with each other. Thus, the lowerhousing 50 may be dimensioned smaller because of the lessened forcesapplied to the lower housing 50.

Other features of the lower housing 50 may be configured to accommodateor counteract the forces of expanding battery cells 54 within thebattery module 22. As illustrated in FIG. 9 , for example, the lowerhousing 50 may include a truss structure 90 to counteract forces of cellstacking and expansion within the lower housing 50. The truss structure90 may be formed along one or both ends 92 of the lower housing 50. Thetruss structure 90 may dissipate forces in a direction of the Y axis 62exerted from the battery cells 54 as they expand due to increasedtemperature within the battery module 22. The expanding battery cells 54may press against each other and/or the ribs 72, transferring theexpansion forces toward the opposite ends 92 of the lower housing 50, asshown by arrows 94. The truss structure 90 may include any desiredpattern of oriented beams and gusseting for moving the force indirections along the X axis 60 as well as the Y axis 62. The illustratedembodiment includes a particular arrangement of adjacent triangularstructures formed partially by inner and outer walls of the lowerhousing 50. The pattern may extend all the way through the height of thelower housing 50 in some embodiments. The truss structure 90 maywithstand expansion forces from the battery cells 54 without addingsubstantial volume or weight to the battery module 22. This may allowthe lower housing 50 to accommodate the expansion of the battery cells54 that occurs throughout the lifetime of the battery cells 54 withinthe battery module 22.

In addition to features for holding and accommodating the expansion ofbattery cells 54, the lower housing 50 may include thermal managementfeatures as well. As illustrated in FIG. 10 , for example, the lowerhousing 50 may include ribs 110 disposed on an outer wall 112 of thelower housing 50. These ribs 110 may function as heat fins, transferringheat from the battery cells 54 within the lower housing 50 to theoutside atmosphere. There may be any desirable number of such ribs 110disposed along the outer wall 112 of the lower housing 50. The ribs 110may be specifically dimensioned and spaced from one another to encourageair flow between the ribs 110 while providing a large surface area alongwhich heat transfer may occur. In some embodiments, the ribs 110 mayenable passive cooling of the battery module 22. In other embodiments,however, the ribs 110 may be used in conjunction with an active coolingcomponent, such as a fan within the vehicle 10, to promote heat exchangethrough the ribs 110. Although only one outer wall 112 of the lowerhousing 50 is shown in the illustrated embodiment, the ribs 110 may bepresent on an opposite outer wall 112 as well. This may ensure thatapproximately the same amount of heat transfer occurs along bothlongitudinal sides of the lower housing 50, and of the battery cells 54disposed therein.

The lower housing 50 may include features for securing the battery cells54, and other battery module components, within the battery module 22.In addition, the lower housing 50 may be configured to secure differentcomponents of the battery module 22 in place relative to one anotherwithout those components being themselves coupled to each other. Forexample, in the illustrated embodiment, the lower housing 50 includesclips 114 protruding upward from the lower housing 50. The clips 114 maybe designed to mate with the lid assembly 56 introduced in FIG. 6 . Thelid assembly 56 may include slots configured to couple with the clips114 on the lower housing 50 to secure the lid assembly 56 relative tothe lower housing 50. It should be noted that in other embodiments, thelower housing 50 may be equipped with a slot for receiving acomplementary clip built into the lid assembly 56, and that in furtherembodiments, the lower housing 50 and lid assembly 56 may includeentirely different types of mating connectors or alternating connectors.

In addition to the clips 114, the lower housing 50 may include a groove116 extending along a circumference of the top portion 80 of the lowerhousing 50. The groove 116 may be configured to mate with acorresponding extension that is built into the cover 52 of the batterymodule 22. FIG. 11 provides an example of the groove 116 of the lowerhousing 50 configured to mate with an extension 117 protruding from thecover 52. In other embodiments, the lower housing 50 may include anextension while the cover 52 is equipped with a complementary groove. Byusing the groove 116 and the extension 117 to mate the lower housing 50and the cover 52, it may be possible to hermetically seal the batterymodule 22. Once positioned within the groove 116, that is, the cover 52may be attached to the lower housing 50 via adhesive, ultrasonicwelding, or any other desirable method for hermetically sealing thebattery module 22. This may prevent moisture, particulate matter, andother foreign agents from entering the more sensitive interiorcomponents of the battery module 22. In the illustrated embodiment, thelower housing 50 and the cover 52 each include lips 118 and 119 thatextend outward beyond the groove 116 and the extension 117,respectively. This may increase the mating surface area between thelower housing 50 and the cover 52, thereby enhancing the seal betweenthe two components.

Battery Terminal Post System and Method of Manufacture

As noted above with reference to FIG. 5 , the battery terminals 24 and26 are designed to protrude from the enclosure formed by the lowerhousing 50 and the cover 52. At one end, these terminals 24 and 26 aredesigned to be coupled to electric equipment within the vehicle 10 via awiring harness, and at an opposite end, the battery terminals 24 and 26are coupled to internal components (e.g., bus bars) of the batterymodule 22. FIG. 12 is a perspective view illustrating the interface ofthe battery terminals 24 and 26 with the internal components of thebattery module 22.

In the illustrated embodiment, the battery terminals 24 and 26 eachinclude straight cylindrical posts configured to carry the outputvoltage (e.g., 48V) of the battery module 22 from the battery cells 54to vehicle components external to the battery module 22. These batteryterminals 24 and 26 may be constructed from copper, or any otherdesirable material that is electrically conductive. The batteryterminals 24 and 26 may be coupled to internal components (e.g., PCBassembly 58) via connectors 120 and 121, respectively. In someembodiments, the connectors 120 and 121 may be electrically coupled to abus bar of the battery module 22. Additionally, in other embodiments theconnectors 120 and 121 may be electrically coupled to a high currentinterconnect 140. In some embodiments, the battery terminals 24 and 26and/or the connectors 120 and 121 may conform to a known standard typeof pin connection. For example, the cylindrical portions of the batteryterminals 24 and 26 may be RADLOCK pins, and the correspondingconnectors 120 and 121 may be RADLOCK connectors used to form theinternal connections between the RADLOCK pins and the PCB assembly 58.Other types of cylindrical posts and/or connectors may be used in otherembodiments.

In the illustrated embodiment, the connectors 120 and 121 used in thebattery module 22 may each conform to a different size and/or shape. Forexample, a RADLOCK #9 connector may be used for the connector 120attaching the first terminal 24 to the PCB assembly 58 and a RADLOCK #10connector may be used for the connector 121 attaching the secondterminals 26 to the PCB assembly 58. In the illustrated embodiment, theconnectors 120 and 121 are bladed connectors configured to couple withthe PCB assembly 58 via bladed portions 122 and 123. Differences betweenthe connectors 120 and 121 may be evidenced in the approximate widthand/or in the bent shape of these bladed portions 122 and 123.Specifically, the bladed portion 122 of the connector 120 may have awidth 124 that is substantially larger than a width 125 of the bladedportion 123 of the connector 121. In addition, in the illustratedembodiment, the bladed portion 122 extends upward (e.g., in a directionof the Z axis 64) to couple the connector 120 to an interconnectcomponent of the PCB assembly 58. The bladed portion 123, however,extends laterally in a direction of the X axis 60 to couple theconnector 121 to another portion of the PCB assembly 58. That is, in theillustrated embodiment, the battery terminals 24 and 26 may have a bentportion between the cylindrical posts and the connector 121. Thedifferent types of connectors 120 and 121 may prevent the batteryterminals 24 and 26 from being connected in reverse during assembly ofthe battery module 22. The cylindrical posts of the battery terminals 24and 26 may or may not conform to the same standard for similar reasons.

In some embodiments, the battery terminals 24 and 26 may be separatecomponents from the connectors 120 and 121. Specifically, thecylindrical posts of the battery terminals 24 and 26 may be screwedinto, laser welded to, or otherwise secured to the connectors 120 and121. In other words, the cylindrical posts of the battery terminals 24and 26 may, in some embodiments, not be integrally connected to theconnectors 120 and 121 because of the additional mechanical connectionsutilized to secure the battery terminals 24 and 26 to the connectors 120and 121. In other embodiments, however, the battery terminal connectors120 and 121 may be integral with the battery terminals 24 and 26. Forinstance, the battery terminals 24 and 26 and the battery terminalconnectors 120 and 121 may be formed from a single piece of materialwithout additional connections (e.g., welds, threads, etc.) couplingcomponents together. The term “integral” refers to the battery terminals24 and 26 being the same piece of material as the battery terminalconnectors 120 and 121 without being welded, bolted, threaded, orotherwise coupled together.

As an example, FIG. 13 illustrates physical changes that are made duringa method of manufacturing one such embodiment of the battery terminal 26that is integral with the battery terminal connector 121. The batteryterminal 26 begins at “step 1” as a substantially straight cylindricalpost of electrically conductive material (e.g., copper). In theillustrated embodiment, the battery terminal 26 includes a flange 126for supporting the battery terminal 26 in an opening of the lowerhousing 50. Below the flange 126, the battery terminal 26 continues toextend along a lower portion 127. The lower portion 127 may becold-formed to create the connector 121 integral with the batteryterminal 26. Cold-forming may involve compressing the lower portion 127until it has a relatively flattened cross section similar to that of abus bar at “step 2”, and bending the flattened lower portion 127 into adesired shape of the connector 121 at “step 3”. Compressing the lowerportion 127 deforms the lower portion 127 such that it is lengthened andflattened, as illustrated.

As a result of the bending shown in “step 3”, the lower portion 127 ofthe battery terminals 24 and 26 may be substantially step shaped. Forexample, in the illustrated embodiment, a first portion 128 of thebattery terminal 26 extends in a horizontal direction aligned with afirst axis 129. A center portion 130 of the battery terminal 26 extendsin a vertical direction aligned with a second axis 131, the second axis131 being substantially perpendicular to the first axis 129 after coldforming. Furthermore, a second portion 132 of the battery terminal 26extends in a horizontal direction along a third axis 133. Asillustrated, the center portion 130 of the battery terminal 26 isdisposed between the first and second portions 128 and 132.Additionally, the first axis 129 and third axis 133 are substantiallyparallel to one another and substantially perpendicular to the secondaxis 131, thereby forming the step shaped lower portion 127 of thebattery terminal 26. To that end, an integral battery terminal connector121 may be formed into this shape from a straight cylindrical postwithout coupling additional components via mechanical connections (e.g.,welding, fasteners). As a result, electrical communication from thebattery cells 54 to the battery terminals 24 and 26 may be improved byreducing or eliminating the resistance due to mechanical connectionsbetween the battery terminals 24 and 26 and the battery terminalconnectors 120 and 121.

As mentioned above, the lower portion 127 may be coupled to a bus bar ofthe battery module 22. The bus bar may transfer electrical energy fromthe battery cells 54. In some embodiments, the lower portion 127 may bewelded to the bus bar of the battery module. Additionally, the lowerportion 127 may be coupled to the high current interconnect 140. Asdescribed in detail below, the high current interconnect 140 may containa slot to receive the connectors 120 and 121 and electrically couple thebattery terminals 24 and 26 to the battery cells 54.

In another embodiment, illustrated in FIG. 14 , the battery terminal 24,the battery terminal 26, or both may be generally U-shaped.Additionally, a first vertical portion of the battery terminal 24 may begenerally cylindrical as described above. However, a second verticalportion may be the bladed connector 121. That is, the second verticalportion may have a substantially flattened cross section. In someembodiments, the bladed connector 121 is welded to the high currentinterconnect 140. As shown, the U-shaped battery terminal 24 may have atransition point where the cross section of the battery terminal 24changes from generally cylindrical to generally flattened. The batteryterminals 24 and 26 may be formed by the cold-forming process describedabove. In a further embodiment, the entire length of the batteryterminals 24 and 26 may consist of a generally cylindrical crosssection, as illustrated in FIG. 15 . In some embodiments, the connector121 of the battery terminal 26 may be welded to a bus bar of the batterymodule 22. Additionally, in the illustrated embodiment, the batteryterminals 24 and 26 include caps 134. The caps 134 are be chamfered androunded to facilitate easy installation of connectors (e.g., RADLOCKconnectors). Moreover, the caps 134 include grooves 135 to furtherenable installation of connectors. It should be noted that differentmethods of manufacture may be used to form a battery terminal connectorthat is integral with the corresponding battery terminal 26. Since thebattery terminal 26 and the connector 121 are made from the same pieceof material in such embodiments, the resistance through the batteryterminal connection is lower than it may be in embodiments where thebattery terminal 26 and the connector 121 are initially separate.

Printed Circuit Board with Shunt

FIG. 16 shows a portion of an embodiment of the PCB assembly 58 withinthe battery module 22. The illustrated PCB assembly 58 includes a singlePCB 136 and a shunt 137 that is directly mounted to the PCB 136. Asnoted above, the battery terminal 26 may be coupled to the PCB assembly58 via the bladed terminal connector 121. For example, the bladedportion 123 of the bladed terminal connector 121 may fit over a topsurface of the shunt 137 to contact the shunt 137 and, in someembodiments, to hold the shunt 137 against a top of the PCB 136 in aclamping manner In other words, the shunt 137 may be held between abottom surface of the bladed portion 123 of the bladed terminalconnector 121 and a top surface of the PCB 136. It should be noted that,in some embodiments, the bladed portion 123 of the bladed terminalconnector 121 may be integral with the bladed terminal connector 121(e.g., as one structure). In other embodiments, the bladed portion 123that contacts the shunt 137 may be a non-integral, separate bus bar ofthe bladed terminal connector 121 that may be welded to the bladedterminal connector 121 after being placed in contact with the shunt 137.For example, in embodiments where the bladed portion 123 is separatefrom the bladed terminal connector 121 (e.g., as shown in FIG. 6 ), thebladed terminal connector 121 may be disposed through an aperture in thelid assembly 56 and proximate the shunt 137, such that the bladedportion 123 may be placed over and in contact with both the bladedterminal connector 121 and the shunt 137 and may be welded (or otherwisecoupled) to these components. In embodiments where the bladed portion123 is integral with the bladed terminal connector 121 (e.g., as shownin FIG. 34 ), the bladed portion 123 may be disposed in contact with theshunt 137, and welded to the shunt 137. Thus, the electrical connectionbetween the shunt 137 and the terminal may be formed without using aseparate process for coupling (e.g., welding) the bladed portion 123 tothe bladed terminal connector 121.

Depending on the arrangement of the battery terminals 24 and 26 of thebattery module 22, at least one of these terminals (e.g., 26) may beelectrically connected, via the shunt 137, with a bus bar 138 located onan opposite side of the PCB assembly 58 from the battery terminal 26.For example, on one end of the shunt 137, the shunt 137 may be held(e.g., clamped) between a bottom surface of the bus bar 138 and a topsurface of the PCB 136 such that the shunt 137 physically contacts thebottom surface of the bus bar 138 and the top surface of the PCB 136,while on the opposite end of the shunt 137, the shunt 137 is disposedbetween the bladed portion 123 and the PCB 136. In such instances,because the bladed portion 123 is coupled or integral with the terminal26, the shunt 137 may function as a low resistance path between theterminal 26 and the bus bar 138. The shunt 137 may also be coupled tovarious conductors (e.g., electrical connections) present on the PCB136, thereby enabling the PCB 136 to monitor the voltage output of thebattery module 22, among other things. In other words, the electricalconnections present on the PCB 136 may be coupled to a measurementdevice or processor such that the measurement device or processor gainsaccess to the shunt 137, via the electrical connections, for measuringthe voltage output.

In the illustrated embodiment, the shunt 137 is directly mounted to thePCB 136 that provides control and monitoring functions to the batterymodule 22. That is, the shunt 137 is in direct contact with and coupledto the PCB 136, instead of being disposed on a separate board or modulethat is coupled to the PCB 136 via wires or ribbon cables. For example,a bottom surface of the shunt 137 may be entirely disposed on a topsurface of the PCB 136. The close proximity of the shunt 137 and the PCB136 may reduce noise over an assembly with a separate shunt and aseparate PCB, where the separate shunt is, for example, coupled to theseparate PCB via wires or ribbon cables. In the illustrated embodiment,by disposing the shunt 137 proximate the PCB 136 (and, thus, proximateelectrical connections and the measurement device of the PCB 136), aclearer signal with reduced noise may be transmitted from the shunt 137through the electrical connections to the measurement device on the PCB136.

Additionally, the shunt 137 may be pressed against the top surface ofthe PCB 136 via a number of components. These components may include,for example, an extension of the bus bar 138, a bladed portion 123 ofthe connector 121, and/or shunt clips 139 of the lid assembly 56. Inparticular, the shunt clips 139 may extend upwardly from the lidassembly 56 and an extension of the shunt clips 139 may extend over theshunt 137. The extension of each shunt clip 139 may extend over theshunt 137 and exert a downward force against the shunt 137, pressing theshunt 137 into place on top of the PCB 136. One or more of the shuntclips 139 may extend through an aperture in the PCB 136. In someembodiments, an adhesive (e.g., a conductive adhesive) may be appliedbetween the shunt 137 and the PCB 136 for coupling the shunt 137directly to the PCB 136. Further, in some embodiments, the shunt 137and/or a footprint of the shunt 137 may be entirely disposed on or overthe PCB 136, such that no portion of the shunt 137 or the footprint ofthe shunt 137 extends beyond sides of the PCB 136. The illustratedarrangement of the shunt 137 in direct contact with the PCB 136, and thefeatures of the shunt 137 in direct contact with the PCB 136 describedabove, may facilitate relatively compact packaging of the PCB assembly58 and simplified manufacturing as compared to a shunt that is mountedseparately from the PCB 136.

As mentioned above, the shunt 137 may provide a low resistanceelectrical path for current originating from the battery cells 54 toflow toward the terminal 26, while aiding in the detection of a voltageoutput from the battery module 22. Specifically, the shunt 137 may beheld in direct contact with an upper surface of the PCB 136 via one ormore of clips, connectors, or adhesive, as described above. The PCB 136may include the electrical connectors with a lead extending out from theupper surface of the PCB 136. Thus, the shunt 137 may be held intophysical and electrical contact with the sensor lead extending from thePCB 136. This lead may communicate an electrical signal to a measurementdevice on the PCB 136. The measurement device may also receive anelectrical signal from a connection to a high current component of thebattery module 22 (e.g., contactor, fuse assembly, bus bar) on anopposite side of the battery cells 54 electrically coupled together. Themeasurement device may then determine a voltage drop between theterminals 24 and 26 of the battery module 22, thus indicating thevoltage output of the battery module 22. Thus, the shunt 137, which isdirectly disposed against the PCB 136, may enable relatively directelectrical connections for determining a voltage output of the batterymodule 22, without the use of additional cables, wires, or otherexternal connectors.

Further, in some embodiments, the shunt 137 may be integral with the PCB136. That is, the shunt 137 may make up a portion of the PCB 136structure. For example, the shunt 137 may be embedded within the PCB 136or the shunt 137 may be an extension of the PCB 136. Accordingly, theelectrical leads of the PCB 136 may extend from the shunt 137 (e.g.,integrated with the PCB 136) to a measurement device of the PCB 136, asdescribed above.

High Current Interconnects Mounted to Printed Circuit Board

To facilitate compact packaging of the battery module, and effectiveelectrical coupling of high current components together within thebattery module 22, the PCB assembly 58 may include one or more highcurrent interconnects 140, as shown in FIG. 17 . Each high currentinterconnect 140 may electrically couple two high current components(e.g., bus bars, fuses, contactors, etc.) to one another. In certainembodiments, the high current interconnect 140 may also be mounted tothe PCB 136, as illustrated in FIG. 17 . The board-mounted high currentinterconnect 140 may couple the two high current components to traces onthe PCB 136 in addition to coupling the high current components to oneanother. In this way, the high current interconnect 140 may act as aninterfacing mechanism between various high current components of thebattery module 22 and the PCB 136.

Turning to FIG. 18 , the high current interconnect 140 may include aframe portion 141, which may be a single piece of conductive materialsuch as copper. The frame portion 141 may include pockets 142A and 142Bformed therein. These pockets 142A and 142B are configured to receivebladed high current components, e.g., the conductive blades or contactsof high current components. Since the frame portion 141 is electricallyconductive, the frame portion 141 may electrical couple the high currentcomponents to each other. In the illustrated embodiment, the pockets142A and 142B are oppositely facing from each other, such that thepocket 142A can receive a bladed component from above and the pocket142B can receive a bladed component from below.

In some embodiments, the frame portion 141 may house a spring 143A and aspring 143B, and these springs 143A and 143B are disposed in the pockets142A and 142B, respectively. The springs 143A and 143B allow one toslide the blades of the high current components into the pockets 142Aand 142B such that the springs 143A and 143B exert a compressive forceon the blades to hold the high current components in place. The springs143A and 143B may be any suitable object made of a conductive materialthat is capable of receiving a bladed high current component in thecorresponding pocket and exerting a compressive force on the bladed highcurrent component. In some embodiments, the springs 143A and 143B mayeach include a relatively flexible sheet of conductive material bent ina U-shape such that opposite sides of the sheet face inwardly towardeach other, as shown in FIG. 18 . The springs 143A and 143B may beformed such that they line the pockets 142A and 142B, respectively. Morespecifically, the springs 143A and 143B may be folded such that oppositesides of the sheets form the inner “walls” of each pocket 142A and 142B.The springs 143A and 143B may also be configured such that portions 144of the springs 143A and 143B directly contact the frame portion 141.

During construction of the high current interconnect 140, the frameportion 141 may be compressed (e.g., stamped) around the springs 143Aand 143B such that only an opening 145A and an opening 145B in the frameportion 141 allows access to the pockets 142A and 142B, respectively.Again, in the illustrated embodiment, the pockets 142A and 142B areoriented towards opposite sides of the frame portion 141 and therespective openings 145A and 145B are on opposite sides of the frameportion 141. This allows the high current interconnect to receive onebladed high current component from above, and one from below.

Further, the frame portion 141 may be compressed such that the openings145A and 145B conform to a desired size based on the high currentcomponents that the high interconnect will couple together. For example,one of the high current components may be a thicker bladed componentthan the other, and the high current interconnect 140 may be constructedaccommodate these different sized bladed components. To that end, theframe portion 141 may be compressed on one side more than on theopposing side such that the openings 145A and 145B (and pockets 142A and142B) are different sizes. For example, in FIG. 18 , the opening 145Ahas a width 146 while the opening 145B has a width 147; as shown, thewidth 146 is smaller than the width 147. For instance, the width 146 ofthe smaller opening may be approximately 0.8 mm, while the width 147 maybe approximately 1.8 mm. By having openings of differing sizes, the highcurrent interconnect 140 may be able to couple high current componentsof differing sizes. In other embodiments, however, the openings 145A and145B may be approximately the same size in order to accommodate highcurrent components of approximately the same size.

Further, as mentioned above, the high current interconnect 140 may bemounted to the PCB 136. To mount to the PCB 136, the frame portion 141may include feet 148 that extend from the frame portion 141 and that maybe welded to the PCB 136. Alternatively or additionally, the PCB 136 maycontain receptacles configured to receive the feet 148 of the highcurrent interconnect 140. For example, the feet 148 of the high currentinterconnect 140 may be disposed in the corresponding receptacles of thePCB 136, and welded to a face of the PCB 136 opposite the side of thePCB 136 from which the frame portion 141 extends.

In addition to mounting to the PCB 136, the high current interconnect140 may be mechanically coupled to high current components of thebattery module 22. As mentioned above, each high current component mayinclude a bladed portion, which is a flattened piece of conductivematerial configured to carry a relatively high current originating fromthe plurality of battery cells 54 in the battery module 22. The bladedportion of a high current component may be inserted into the pocket 142Aor 142B via the respective opening 145A or 145B, such that the bladedportion directly contacts the corresponding spring 143A or 143B. Thesprings 143A and 143B, which form the walls of the pockets 142A and142B, exert a compressive force on the bladed portion disposed withinthe corresponding pocket. This compressive force may reduce the effectof any forces that might otherwise remove the bladed portion from thepocket 142A or 142B, thereby securing the bladed components in the highcurrent interconnect 140. As a result, the high current interconnect 140may be mechanically coupled to the bladed portions of the high currentcomponents without the use of additional fasteners to secure the bladedportions in place. Foregoing the additional fasteners may reduce thecomplexity of manufacturing and assembling the PCB assembly 58, since noadditional screws, bolts, or other fastener components have to behandled.

It should be noted that the compressive force exerted by the springs143A and 143B may still allow for small movements of the bladed portionswithin the pockets 142A and 142B. For example, as the battery module 22may be disposed within a vehicle, the springs 143A and 143B may allowfor slight shifts of the bladed portions up and down within the pockets142A and 142B that may occur during movement of the vehicle. This makesthe high current interconnect 140 a relatively flexible mechanicalcoupling feature. This flexibility would not be possible using otherfasteners (e.g., bolts, screws) or welding to join the high currentcomponents, since these joining methods do not allow for slightmovements of the bladed components relative to each other.

In addition to mechanically coupling the high current componentstogether, the high current interconnect 140 electrically couples thehigh current components together. Further, the high current interconnect140 is designed to be electrically coupled with the PCB 136 as well. Acurrent flow 149 illustrated in FIG. 19 depicts how the high currentinterconnect 140 may be electrically coupled to two high currentcomponents and to traces on the PCB 136. Current may flow from a bladedportion 150 of a first high current component disposed in the pocket142A to the conductive spring 143A that directly contacts the bladedportion 150. Current may then flow from the spring 143A to the frameportion 141 via the portions 144 that contact the frame portion 141. Asthe frame portion 141 is entirely conductive, the current that flowsinto the frame portion 141 may flow from the spring 143A to the spring143B. Specifically, the current may flow through an outer layer of theframe portion 141 that wraps around both of the springs 143A and 143B,as well as through an inner layer located directly between the springs143A and 143B. Current may then flow from the spring 143B to a bladedportion 151 of a second high current component disposed in the pocket142B that directly contacts the spring 143B. Current may also flow fromthe frame portion 141 into the feet 148 that extend into the PCB 136.One or more traces 152 on the PCB 136 may be in contact with the feet148 to detect the current flow. Thus, the feet 148 of the high currentinterconnect 140 may provide both a mechanical connection and anelectrical connection between the high current components disposed inthe high current interconnect 140 and the PCB 136.

As illustrated and discussed above, the high current interconnect 140(i.e., frame portion 141, springs 143A and 143B, and feet 148) may beelectrically coupled to the high current components and to traces on thePCB 136. Because the high current interconnect 140 is entirelyconductive, the high current components and the PCB 136 are effectivelyelectrically coupled to one another by virtue of their electricalcoupling to the high current interconnect 140. This may allow the highcurrent interconnect 140 to electrically couple high current componentsand the PCB 136 to one another without the use of cabling and othermeans traditionally used to make electrical connections betweencomponents and connectors. Foregoing cabling and similar means to formelectrical connections between the high current components may reducethe complexity of manufacturing and assembling the PCB assembly 58 andmay reduce the space requirements of the PCB assembly 58 within thebattery module 22.

Multiple high current interconnects 140 may be used within the batterymodule 22 to electrically couple various high current components witheach other and the PCB 136, while minimizing spatial requirements of thePCB assembly 58. FIG. 20 illustrates certain components of the PCBassembly 58, including various high current bladed components that maybe coupled to one another and to the PCB 136 via the high currentinterconnects 140. These high current components include, for example, afuse assembly 153, a contactor 154, a bus bar 155, and the terminalconnector 120. The fuse assembly 153 includes a fuse 156 configured toprovide overcurrent protection to the PCB assembly 58. The fuse 156 maybe coupled to the terminal connector 120 via a high current interconnect140A and to the contactor 154 via a high current interconnect 140B. Thefuse 156 may be coupled to the high current interconnects 140A and 140Bvia bladed fuse connectors 157, which are discussed in detail below. Thecontactor 154 is a device used to switch the high current power circuiton, allowing the battery module 22 to output power, as discussed indetail below. As shown in FIG. 21 , the contactor 154 may include a highcurrent blade 158A and a high current blade 158B. The high current blade158A may be coupled to the fuse 156 via the high current interconnect140B. The high current blade 158B may be coupled to the bus bar 155, andsubsequently the battery cells 54, via the high current interconnect140C. Traces for a voltage sensing component and a pre-charge circuit,both disposed on the PCB 136, may be in contact with the high currentinterconnects 140B and 140C, allowing the voltage sensing component andthe pre-charge circuit to electrically couple to the contactor 154 inorder to detect the voltage across the contactor 154. It should be notedthat the illustrated embodiment provides only one example of differentcombinations of high current components that may be electrically coupledto one another and to the PCB 136 via the high current interconnects 140mounted on the PCB 136.

The disclosed high current interconnects 140 may enable relativelysimple assembly of the battery module. For example, the high currentinterconnect 140 may include feet 148 that that may be welded to the PCB136 and/or the traces 152 disposed on the PCB 136 may be welded to thefeet 148. These welding processes may form mechanical and electricalcouplings between the high current interconnect 140 and the PCB 136.Additionally, in embodiments in which the PCB 136 contains receptaclesconfigured to receive the feet 148, the feet 148 of the high currentinterconnect 140 may be disposed in the corresponding receptacles of thePCB 136, before any welding processes are performed. After the highcurrent interconnect 140 is mounted to the PCB 136 and secured in thismanner, the bladed portions of high current components may be inserteddirectly into the pockets 142A and 142B of the high current interconnect140 without the use of additional fasteners. In sum, assembly of thehigh current interconnect 140 may consist essentially of welding thefeet 148 of the high current interconnect 140 to the PCB 136 and thetraces 152 disposed on the PCB 136 and inserting the bladed portions ofthe two high current components into the pockets 142A and 142B.

In some embodiments, the high current interconnects 140 may be mountedon either side of the PCB 136 to more easily facilitate couplingsbetween the high current components of the PCB assembly 58 and the PCB136. For example, FIGS. 20 and 21 depict the PCB assembly 58 such thatif the PCB assembly 58 was disposed above the battery cells 54, then thehigh current interconnects 140 would extend above the PCB 136 and awayfrom the battery cells 54. In such a configuration, the high currentinterconnects 140 may each receive a bladed high current component fromabove and another bladed high current component extending upward frombelow the PCB 136. In contrast, FIG. 22 depicts the PCB assembly 58configured such that the high current interconnects 140 extend below thePCB 136 and towards the battery cells 54. In this particularconfiguration, the high current interconnects 140 may each receive abladed high current component from below and another bladed high currentcomponent extending downward from above the PCB 136. As will beappreciated, in some embodiments, one or more high current interconnects140 may be mounted to the PCB 136 such that some high currentinterconnects 140 extend above the PCB 136 and other high currentinterconnects 140 extend below the PCB 136. Any desirable spatialconfiguration of the high current interconnects 140 above or below thePCB may be used to reduce the overall packaging size of the batterymodule 22.

Solid State Pre-Charge Control

The pre-charge control circuit 159 on the PCB 136 may be used topre-charge a DC bus 160 on the output of the battery system 20. Asillustrated in FIG. 19 , a pre-charge control circuit 159 may beincluded within the battery module 22. In this position, the pre-chargecontrol circuit 159 may control a charge applied to a DC bus 160 fromthe battery module 22. The DC bus 160 may couple the battery module 22to various electric components 161 of the vehicle 10. Prior to applyinga full-source voltage of the battery module 22 to the DC bus 160, the DCbus 160 may charge using a lower voltage until a predetermined voltagelevel is reached. A capacitor or capacitor bank 162 disposed between ahigh-side and a low-side of the DC bus 160 may allow the DC bus 160 togradually charge to a predetermined level, as described in detail below.Upon reaching the predetermined level of charge at the DC bus 160, thebattery module 22 may apply the full-source voltage to the DC bus 160 toprovide a voltage source to the electric components 161 of the vehicle10.

In traditional battery systems, the pre-charge control circuit 159 isoften implemented within the wiring harness of the vehicle 10, and noton the PCB 136 or even within the battery module 22. Providing thepre-charge control circuit 159 on the PCB 136 with solid statecomponents may provide a more integrated and space efficient batterysystem than implementing the pre-charge circuit within the wiringharness. The solid state components included the pre-charge controlcircuit 159 may include transistors, microprocessor chips, diodes, orany other components built from solid materials. For example, thepresently disclosed pre-charge control circuit 159 may be positioned onthe PCB 136 in such a manner as to occupy around 4.5 cubic inches ofvolume.

With the foregoing in mind, a description of an embodiment of apre-charge control circuit that may be employed on the PCB 136 isprovided. Turning to FIG. 20 , a diagrammatical representation of thepre-charge control circuit 159 is illustrated. It should be noted thatthe pre-charge control circuit 159 is shown as an example and as asingle embodiment of the disclosure. As such, it may be appreciated thatthe pre-charge control circuit 159 may have a variety of circuitconfigurations not discussed in the present disclosure, but stillfalling under the true spirit of the disclosure.

The pre-charge control circuit 159 may include a pre-charge input pin163 and an override input pin 164 as controlling inputs. The pre-chargeinput pin 163 may provide a signal to an AND gate 165 that may signal tothe pre-charge control circuit 159 to run a pre-charge. Since theillustrated pre-charge input pin 163 is coupled to the AND gate 165, ahigh signal provided at the pre-charge input pin 163 may be a voltagehigh enough to satisfy a threshold level of the AND gate 165 when thesignal is intended to activate a pre-charge mode. Likewise, a low signalmay be any voltage low enough to fall under the threshold level of theAND gate 165 when the signal is not intended to activate the pre-chargemode. Additionally, the override input pin 164 may provide the othercontrolling input into the AND gate 165. This signal may originate froma system designed to disengage all processes that are carried out on thePCB 136 regardless of any other activation input signal of theprocesses. Generally, the override input pin 164 of the AND gate 165receives a high signal during ordinary operating conditions. Upon adetected fault within the battery system 20, a low signal may betransmitted at the override input pin 164 to deactivate the pre-chargemode regardless of the signal at the pre-charge input pin 163.

The AND gate 165 may function using standard and gate logic. Anintegrated circuit power supply 166 may provide power to the AND gate165 and a ground 167 may ground the AND gate 165. When the signals atthe pre-charge input pin 163 and at the override input pin 164 are bothhigh (e.g., above a voltage threshold), the output of the AND gate 165may also be a high signal. Additionally, when either or both of thesignals into the pre-charge input pin 163 and the override input pin 164are low (e.g., below the voltage threshold), the output of the AND gate165 may also be a low signal. In this manner, the pre-charge input pin163 and the override input pin 164 may activate the pre-charge mode uponreceiving a high signal into both of the input pins 163 and 164.

A transistor 168 may interact with an output signal of the AND gate 165.Upon receiving a high signal from the AND gate 165 at a base of thetransistor 168, the transistor 168 may be activated resulting in a lowresistance path between a collector and an emitter of the transistor 168toward the ground 167. Further, the low resistance path across thetransistor 168 may ground a battery pack voltage source 169 (e.g., thebattery system 20). Grounding the battery pack voltage source 169 mayactivate a power metal-oxide-semiconductor field effect transistor(MOSFET) 171, which may result in a flow of current toward a pre-chargeoutput 170.

To activate the power MOSFET 171 and enable the current flow toward thepre-charge output 170, a voltage difference between the battery packvoltage source 169 and a voltage at a node 172 must surpass a voltagethreshold of the power MOSFET 171. When the voltage threshold of thepower MOSFET 171 is surpassed, the power MOSFET 171 may become a lowresistance path for the current flow toward the pre-charge output 170.Additionally, without resistors 173 and 174 dividing the voltagesupplied by the battery pack voltage source 169, the voltage at the node172 may be equal to the voltage supplied by the battery pack voltagesource 169. With the resistors 173 and 174 in place, the resistors 173and 174 may divide the voltage supplied by the battery pack voltagesource 169 at node 172 resulting in the voltage difference between asource and a gate of the power MOSFET 171. This voltage difference maybe large enough to surpass the voltage threshold of the power MOSFET171, thus resulting in activation of the power MOSFET 171.

It may be appreciated that the battery pack voltage source 169 may be a48V battery system. Further, the pre-charge control circuit 159, in someembodiments, may have a configuration that controls the pre-charge for avariety of levels of voltage sources other than a 48V battery system. Assuch, the power MOSFET 171 may include various MOSFETs with parametersthat may vary based on a variety of voltage levels available for thebattery pack voltage source 169. Further, the resistors 173 and 174 mayhave varying resistances based on the threshold voltage of the powerMOSFET 171 and the voltage supplied by the battery pack voltage source169.

After activation of the power MOSFET 171, the voltage from the batterypack voltage source 169 may activate a diode 175 and be supplied atresistors 176. The resistors 176, in combination with resistors 177, mayprovide another voltage divider of the voltage from the battery packvoltage source 169. Resistances of the resistors 176 and 177 may bechosen such that a current entering the pre-charge output 170 may besufficiently low for a controlled rise of a voltage level of thecapacitor 162 coupled across the DC bus 160 at an output of the batterymodule 22. For example, the resistors 176 may each have a resistance ofaround 10 ohms and the resistors 177 may each have a resistance ofaround 100 kilohms. With a 48V source, the current entering thepre-charge output 170 may be limited to less than 0.25 mA. By chargingthe capacitor 162 across the DC bus 160 with such a low current prior toapplying a full source voltage from the battery pack voltage source 169,an undesirable in-rush current may be avoided when the full sourcevoltage is applied after the pre-charge is complete.

Certain features of the pre-charge control circuit 159 may increase thereliability and lifespan of the pre-charge control circuit 159. Asillustrated in FIG. 20 , for example, the resistors 176 may beimplemented as multiple lower resistance resistors rather than anindividual resistor with a resistance equivalent to the sum of themultiple resistances. By employing the multiple resistors 176, themultiple resistors 176 may spread out heat dissipation resulting from avoltage drop across the resistors 176. This may prolong the life of theresistors 176, resulting in enhanced reliability of the pre-chargecontrol circuit 159 for a longer amount of time than if the resistors176 were consolidated into a single resistor. Additionally, the diode175 may also enhance the reliability of the pre-charge control circuit159. The diode 175 may be positioned at any point on a path extendingbetween the power MOSFET 171 and the pre-charge output 170. In FIG. 19 ,the diode 175 is illustrated coupled between the power MOSFET 171 andthe resistors 176, but the diode 175 may also be coupled at any locationbetween the resistors 176 and the pre-charge output 170. Further, thediode 175 may function to protect the pre-charge control circuit 159from the vehicle 10 potentially back-feeding energy into the pre-chargecontrol circuit 159 and overcharging the battery system 20. The diode175 is forward biased toward the pre-charge output 170. Therefore,should the vehicle 10 back-feed excess energy toward the battery system20, the diode 175 may protect the pre-charge control circuit 159.

As mentioned above, the disclosed pre-charge control circuit 159 may beused to pre-charge a DC bus 160 at the output of the battery module 22.To illustrate this function, FIG. 21 is a process flow diagram of amethod 178 of pre-charging the DC bus 160 at the output of the batterymodule 22. Initially, the method 178 may initiate at block 179 with adetermination of whether an override is disabled. As discussed above,the override may be disabled when the signal entering the AND gate 165at the override input pin 164 is a high signal. The high signal enteringthe AND gate 165 at the override input pin 164 may enable the pre-chargecontrol circuit 159 to execute the pre-charge if an appropriatepre-charge input signal is received at the pre-charge input pin 163. Ifthe override is enabled, then the pre-charge control circuit 159 may notexecute the pre-charge, and the determination of whether the override isdisabled, at block 179, may repeat until the determination is made thatthe override is disabled.

Upon determining (block 179) that the override is disabled, the method178 may include determining at block 180 a presence of a pre-chargeactivation signal. Specifically, at block 180, the pre-charge controlcircuit 159 may receive a signal from a processor within the batterysystem 20 instructing the pre-charge control circuit 159 to pre-chargethe DC bus 160. If the pre-charge control circuit 159 does not receivethe signal, then a pre-charge may not occur, and the method 178 mayrestart at the override determination of block 179. However, uponreceipt of the pre-charge activation signal, the pre-charge controlcircuit 159 may begin applying (block 181) the current controlledvoltage of the pre-charge control circuit 159 to the DC bus 160 at theoutput of the battery system 20. After applying the voltage to the DCbus 160 at block 181, a first reading of a voltage at the DC bus 160 maybe taken at the start of the voltage application (block 182A), and thena second reading may be taken a short time later at block 182B. By wayof example, the second voltage reading of the DC bus 160 may be taken20-30 milliseconds after the initial reading.

Next, at block 183, the two voltage readings of the DC bus 160 arecompared to determine if there is a short-circuit in the DC bus 160resulting in the capacitor 162 not charging. This may be accomplished bydetermining if there is any movement of the voltage on the DC bus 160from the first reading to the second reading. If there is an increase involtage on the DC bus 160, then the pre-charge of the DC bus 160 may befunctioning appropriately. On the other hand, if no movement of voltagebetween the first and the second reading is observed, the readings mayindicate that there is a short-circuit resulting in a malfunction of thepre-charge. Additionally, should the capacitor 162 fail to charge, thepre-charge of the DC bus 160 may not be successful. Because of theunsuccessful pre-charge, applying the full source voltage to the DC bus160 may result in an undesirable response.

Further, observing and responding to a short-circuit based on thereadings, at block 183, may be enabled through the use of semiconductorcomponents to operate the pre-charge control circuit 159. In atraditional, relay-based pre-charge circuit, the contactors are notcapable of identifying and responding to a short-circuit with adequatespeed. Because it would not take long for the short-circuit to impactthe electric components 161 coupled to the DC bus 160, the speed of thesemiconductor components of the pre-charge control circuit 159 mayprovide particular value to the disclosed battery system 20.

When the readings do indicate a short-circuit at block 183, thepre-charge control circuit may automatically shut down the pre-chargeand indicate a short-circuit error at block 184. Additionally, the fullsource voltage may not be applied to the DC bus 160 until theshort-circuit error is resolved and the pre-charge is completed. In thismanner, the pre-charge control circuit 159 may protect the DC bus 160and the electric components 161 coupled to the DC bus 160 from excessiveinrush currents that would otherwise result upon applying the fullsource voltage to an uncharged DC bus 160.

Moreover, if the indication at block 183 is that there is noshort-circuit, then the pre-charge may continue for a full pre-chargecycle at block 185. In order for the full pre-charge cycle to happen,the current controlled voltage of the pre-charge control circuit 159 maybe applied to the DC bus 160 for a period of time sufficient to chargethe capacitor 162 across the DC bus 160. Further, the pre-charge controlcircuit 159 may charge the capacitor 162 to a threshold percentage ofthe voltage of the battery pack voltage source 169 prior to applying thefull source voltage. For example, the threshold percentage of thecapacitor 162 may be 90-95% of the voltage provided by the battery packvoltage source 169. Therefore, with a 48V battery module 22, thecapacitor 162 may be charged for long enough to reach approximately 45Vbefore applying the full source voltage of the 48V battery module 22across the DC bus 160. Further, the amount of time that it may take forthe capacitor 162 to charge to the threshold percentage may depend uponthe current supplied at the DC bus 160. The pre-charge control circuit159 may control the flow of current toward the DC bus 160. Therefore,the pre-charge may be programmed to run for a slightly longer amount oftime than an expected time for the capacitor 162 to reach the thresholdpercentage based on a typical flow of current out of the pre-chargecontrol circuit 159. For instance, once it is established in block 183that there is not a short-circuit, the pre-charge may run for anadditional 250 milliseconds before the processor disables the pre-chargecontrol circuit 159.

Finally, once the processor shuts off the pre-charge control circuit 159after block 185, the process may start over at block 179 and wait forthe appropriate input signals that may indicate that another pre-chargeshould occur. Even though the capacitor or capacitor bank 162 across theDC bus 160 may have a very large capacitance and may hold charge for anextended time, the capacitor 162 may be discharged every time that thevehicle 10 stops moving. Therefore, the method 178 of pre-charging theDC bus 160 illustrated by the process flow diagram of FIG. 25 may occurseveral times on each trip taken by the vehicle 10.

Constant Current Relay Control for Battery Systems

The PCB 136 may include additional hardware for controlling certainaspects within the battery module 22. For example, in some embodiments,the PCB 136 may provide hardware based current control that tightlycontrols the current in a relay coil of the contactor 154. The contactor154 may include an electrically controlled switch to electrically couplethe battery cells 54 to the battery terminals 24 and 26 when thecontactor 154 is in a closed position. The contactor 154 may alsoinclude a relay coil that receives a voltage controlled by the hardwarebased control circuit and generates a magnetic field to actuate theswitch of the contactor 154. The hardware based control may reduce anamount of electromagnetic interference and stress on the contactorrelay, by lowering the amount of current that is supplied to thecontactor 154 throughout the life of the battery module 22. Adiagrammatical representation of one example of a relay control circuit186 that may be used to perform this control is illustrated in FIG. 21 .The relay control circuit 186 may remove a delay in responsiveness thata software based relay control may exhibit due to looped timing. As aresult, the current through the relay coil of the contactor 154 mayremain constant and immune to fluctuations in battery voltage. This mayreduce the heat generated in the relay coil and eliminate undesirableeffects due to rapid changes in battery voltage.

Again, FIG. 21 illustrates one embodiment of the relay control circuit186 that may be mounted on the PCB 136. As such, it should be noted thatother embodiments of the relay control circuit 186 may have a variety ofcircuit configurations not discussed in the present disclosure, butstill falling under the true spirit of the disclosure. In theillustrated embodiment, the relay control circuit 186 is configured toreceive a high-side enable input 187 and a low-side enable input 188.The inputs 187 and 188 may be fed into a high-side AND gate 189 and alow-side AND gate 190, respectively. High signals and low signals may beprovided to the inputs 187 and 188, and these signals may originate froma processor 191 implementing instructions stored in a memory device. Theprocessor 191 may provide signals to the relay control circuit 186 thatcontrol voltage application to the contactor 154 in a hardware basedscheme.

As noted above, the processor 191 may provide signals to the high-sideenable input 187 and the low-side enable input 188. For example, a highsignal (i.e., an enable signal) entering the high-side enable input 187may instruct the relay control circuit 186 to enable an application ofvoltage at a high-side of the contactor 154. Applying voltage at thehigh-side of the contactor 154 may enable switching of the contactor154, as discussed in detail below. Further, a high signal at thelow-side enable input 188 may instruct the relay control circuit 186 toenable a current to flow from a low-side of the contactor 154 back intothe relay control circuit 186. In contrast, a low signal (i.e., adisable signal) at the high-side enable input 187 may prevent thecurrent from flowing through the contactor, and thus from closing thecontactor or maintaining the contactor in a closed position, by removinga path to ground for the current to flow toward. Additionally, a lowsignal at the low-side enable input 188 may increase an amount of timeto open the contactor 154 after it is in the closed position, and a lowsignal is also provided to the high-side enable input 187.

In addition to the inputs 187 and 188, the AND gates 189 and 190 mayalso have override input pins 164, similar to the override input pin 164of the pre-charge control circuit 159. As discussed above in the solidstate pre-charge control section, the override input pins 164 mayreceive a signal that originates from a system designed to disengage allprocesses that may be carried out on the PCB 136 regardless of any otheractivation instructions received by the various processes. Generally, ahigh signal may be provided at the override input pin 164 of the ANDgates 189 and 190 during ordinary operating conditions. Upon a detectedfault within the battery system 20, a low signal may be transmitted tothe override input pins 164 to deactivate the relay control circuit 186.Deactivating the relay control circuit 186 may result in the contactor154 moving to an open position.

Further, the AND gates 189 and 190 may function similarly to the ANDgate 165 in that when the AND gates 189 and 190 receive two high signalsat their respective inputs 164, 187, and 188, the AND gates 189 and 190may output a high signal. Additionally, should one or both of the inputs164, 187 of the AND gate 189 be a low signal, the AND gate 189 mayoutput a low signal. Similarly, if one or both of the inputs 164, 188 ofthe AND gate 190 be a low signal, the AND gate 190 may output a lowsignal. The signals produced by the AND gates 189 and 190 may provide amechanism to control the current flowing through the contactor 154.

When the AND gate 189 outputs a high signal, a transistor 192 mayreceive the high signal at a base of the transistor 192. Further, thehigh signal applied at the base of the transistor 192 may activate thetransistor 192, completing a path from the battery pack voltage source169 (e.g., plurality of battery cells 54) to the ground 167 for currentto flow. A result of closing the path to the ground 167 may be thatresistors 193 and 194 divide a voltage originating from the battery packvoltage source 169. Dividing the voltage may result in a voltagedifferential between a voltage level at a node 195 applied to a gate ofa power metal-oxide-semiconductor field-effect transistor (MOSFET) 196and the voltage of the battery pack voltage source 169 applied to asource of the power MOSFET 196. It may be noted that while FIG. 21illustrates the power MOSFET 196, a power transistor other than a powerMOSFET may also be applied in the relay control circuit 186 in place ofthe power MOSFET 196. The voltage differential may activate the powerMOSFET 196, closing a switch between the battery pack voltage source 169and a high-side 197 of the contactor 154.

Additionally, a high-side diagnostic feedback output 198 may providefeedback to the processor 191 indicating functionality of the circuitrycoupled to the high-side 197 of the contactor 154. The diagnosticfeedback output 198 may include, for example, an indication of whetherthe power MOSFET 196 and the transistor 192 are switching properlyduring high-side enable and high-side disable time periods (e.g.,diagnosing the functionality of the relay coil of the contactor 154).Further, the diagnostic feedback output 198 may provide an indication tothe processor 191 of a short circuit along circuitry coupled to thehigh-side of the contactor 154.

When the low-side enable input 188 receives a high signal, the relaycontrol circuit 186 may continuously dissipate at least a portion of theenergy from the contactor 154. More specifically, circuitry on alow-side 199 of the contactor 154 may function by providing a pathtoward the ground 167 for the current entering the circuitry from thelow-side 199 of the contactor 154 when the low-side enable input 188 andthe override input pin 164 both receive high signals. When both inputs164 and 188 to the AND gate 190 receive high signals, the AND gate 190may output a high signal. The high signal output by the AND gate 190 mayactivate a power MOSFET 200 resulting in the path toward the ground 167for current flowing from the low-side 199 of the contactor 154.Continuously dissipating energy on the low-side 199 of the contactor 154in this manner may provide for rapid dissipation of energy stored in acoil of the contactor 154 through the load resistance of the circuitryof the low-side 199 of the contactor 154. This may enable a quickrelease of a switch of the contactor 154. Thus, enabling circuitry on alow-side 199 of the contactor 154 may also assist in switching thecontactor 154 back to an open position after the contactor 154 hasalready been pulled-in. It should be noted that the low-side enableinput 188 may receive a high signal at all times during normal operationof the relay control circuit 186. As a result, the relay control circuit186 may generally be controlled via the high-side enable input 187 asdiscussed above while the low-side enable input 188 generally receives aconstant high signal.

Additionally, the relay control circuit 186 may include a diagnosticfeedback output 201 to provide an indication of whether the power MOSFET200 is switching properly. In some instances, the diagnostic feedbackoutput 201 may provide signals that enable the processor 191 to diagnoseany problems that may arise with the relay coil of the contactor 154.For example, a signal at the diagnostic feedback output 201 may providea signal indicating that the relay coil is even when the high-sideenable 187 instructs the relay control circuit 186 to close. In thismanner, a signal may provide an indication that the relay controlcircuit 186 is not functioning desirably.

The relay control circuit 186 may also include an operational amplifier(op-amp) 202 that may receive a voltage signal at a positive terminal ofthe op-amp 202. In the illustrated embodiment, the op-amp 202 mayfunction as a current measurement device. The current measurement devicemay indicate a current level flowing from the contactor 154 to providesignals to the processor 191 for current control operation (i.e.,activating or deactivating the power MOSFET 196 based on the signalsprovided to the processor). Further, the voltage signal received by theop-amp 202 may be a voltage level representative of the current flowingfrom the low-side 199 of the contactor 154 to the relay control circuit186. The op-amp 202 may amplify the voltage signal received by theop-amp 202 and provide an amplified signal representative of the currentlevel flowing from the contactor 154 to the processor 191. A referencebuffer voltage source 203 may provide a signal to the positive terminalof the op-amp 202 to set an input offset current for the op-amp 202. Theinput offset current may establish a zero point for current entering thepositive terminal of the op-amp 202. This may allow the relay controlcircuit 186 to enable a determination of the exact current supplied fromthe low-side 199 of the contactor 154. The op-amp 202, in anon-inverting, negative feedback configuration, as illustrated in FIG.21 , may provide amplification of the voltage signal applied at thepositive terminal by a value established by resistance values ofresistors 204 and 205 at an output of the op-amp 202.

In some embodiments, the input offset current may be established by avoltage divider consisting of resistors 206 and 207. The resistors 206and 207 may establish the input offset current by dropping a voltagefrom the reference buffer voltage source 203 across the resistor 206,resulting in a known current value flowing at a known voltage toward thepositive terminal of the op-amp 202. The input offset current mayestablish a known difference in current between the positive terminaland a negative terminal of the op-amp 202. Using the input offsetcurrent as a zero point, the current flowing from the low-side 199 ofthe contactor 154 may be approximated.

Subsequently, the output of the op-amp 202 flows to an analog-to-digital(A/D) converter 208 at an analog input AIN1 of the A/D converter 208.The A/D converter 208 may be powered by a voltage source 209 andgrounded at the ground 167. Further, the A/D converter 208 may samplethe output of the op-amp 202 to provide a digital representation of thecurrent level flowing from the low-side 199 of the contactor 154 to theprocessor 191 at a digital output DOUT of the A/D converter 208. Thatis, the A/D converter 208 may receive an analog signal from the outputof the op-amp 202 and convert the analog signal to a digital signalprior to providing the digital signal to the processor 191. Theprocessor 191 may read the digital representation of the current levelflowing from the low-side 199 of the contactor 154 at each pulse of theA/D converter 208. After the pulse is read, the value may be compared bythe processor 191 to a look-up table stored in a memory to determine anapproximated current level, and the processor 191 may determine if theapproximated current level falls within an acceptable current levelrange. The comparison may result in the processor 191 controlling thesignal entering the high-side enable input 187 based on where thedigital representation may be in relation to stored threshold values (asdiscussed in detail below). Further, the voltage from the referencebuffer voltage source 203 may be applied to a reference (REF) pin of theA/D converter 208 to supply a precision voltage for the output of theop-amp 202 to be compared against for accuracy of the digitalrepresentation.

The processor 191 may control the signals entering the inputs 187 and188 based on the measured current level received from the A/D converter208 to control the current in a pull-in mode and a hold mode. Toillustrate this current control, FIG. 22 is a plot 430 of a currentlevel 432 measured at the low-side 199 of the contactor 154 in the relaycontrol circuit 186 as a function of time. To begin with, the currentlevel 432 may represent the approximate current level measured on alow-side of the contactor 154 in the relay control circuit 186 when thehigh-side enable input 187 receives a low signal input. The low-signalinput may result in disengaging the battery pack voltage source 169 fromthe contactor 154. Disengaging the battery pack voltage source 169,after an appropriate amount of discharge time, may remove any charge orcurrent from the contactor 154 as measured in the relay control circuit186. Further, even though the coil in the contactor 154 may be entirelydischarged (i.e., the contactor 154 is open and current may not flowthrough the contactor 154), the current level 432 may be a value greaterthan zero based on the input offset current established by the referencebuffer voltage source 169 and the resistors 206 and 207, as describedabove.

Upon receiving an indication to pull-in the contactor 154, the processormay instruct the relay control circuit 186 to function in a pull-in mode434. During the pull-in mode 434, the processor 191 may provide a highsignal at the high-side enable input 187, resulting in voltage from thebattery pack voltage source 169 being applied to the high-side 197 ofthe contactor 154. The current across the relay coil of the contactor154 may increase as a result of applying the voltage from the batterpack voltage source 169. At a current level 436, as illustrated in FIG.22 , the contactor 154 may close, as marked by a peak and a slight dropin current flowing across the contactor 154. During the pull-in mode434, the current across the contactor 154 may continue to increase untilthe current reaches a pull-in mode upper threshold current 438. Uponreaching the pull-in mode upper threshold current 438, the processor 191may provide a low signal to the high-side enable input 187 to disengagethe battery pack voltage source 169 from the contactor 154.

After disengaging the battery pack voltage source 169, the measuredcurrent may reach a pull-in mode lower threshold current 440. When thepull-in mode lower threshold current 440 is reached, the high-side mayagain be enabled with a high signal to the high-side enable input 187.As shown in FIG. 22 , this process may continue in until a predeterminedtime limit for the pull-in mode 434 is reached. Thus, the pull-in mode434 may involve cycling between engaging and disengaging the batterypack voltage source 169 with the contactor 154 to maintain a moretightly controlled current level during the pull-in mode than what asoftware control scheme achieves. Therefore, the relay control circuit186 may maintain a substantially constant current (i.e., between thepull-in mode upper threshold current 438 and the pull-in mode lowerthreshold current 440) for the duration of the pull-in mode 434.Additionally, the predetermined time limit for the pull-in mode 434 maybe determined based on an expected time for the contactor 154 topull-in. Further, the predetermined time limit may be greater than theexpected amount of time to transition the contactor switch from the openposition to the closed position. For example, in the plot 430, thepull-in mode is set to around 200 ms, which is slightly longer than theamount of time taken for the contactor 154 to transition to the closedposition. The pull-in mode may be set longer or shorter based on theexpected time for the contactor 154 to pull-in as well as additionaltime to account for a margin of error.

Once the predetermined time limit for the pull-in mode 434 is reached,the processor may transition to a hold mode 442. The hold mode 442 maymaintain the contactor in the closed position (i.e., enabling powertransmission from the battery pack voltage source 169 to the electricalcomponents of the vehicle 10) while drawing less power than the pull-inmode 434. During the hold mode, the processor may provide a low signalto the high-side enable input 187 that may result in disengaging thebattery pack voltage source 169 from the contactor 154 and lowering thecurrent measured at a low-side of the contactor 154 in the relay controlcircuit 186. The low signal at the high-side enable input 187 may becontinuous during the hold mode 442 until the current measured in therelay control circuit 186 reaches a hold mode lower threshold current444. Upon the measured current reaching the hold mode lower thresholdcurrent 444, the processor 191 may provide a high signal to thehigh-side enable input 187, thereby engaging the battery pack voltagesource 169 with the contactor 154 and increasing the current measured bythe relay control circuit 186. The high signal may continue at thehigh-side enable input 187 until the current reaches a hold mode upperthreshold current 446.

In a similar manner to the pull-in mode 434, the processor 191 mayrepeatedly cycle between engaging and disengaging the battery packvoltage source 169 until the processor 191 receives a signal instructingthe processor 191 to open the contactor 154. The result may be a tightlycontrolled current level that is lower than the current level during thepull-in mode 434. Therefore, the relay control circuit 186 may maintaina substantially constant current (i.e., between the hold mode upperthreshold current 446 and the hold mode lower threshold current 444) forthe duration of the hold mode 442. This is possible because the amountof current needed to maintain the contactor 154 in a closed position isless than the current needed to move the contactor 154 from an openposition to the closed position. Further, the speed of solid statecontrol components of the relay control circuit 186 may enable a fasterresponse time to voltage lags from the battery pack voltage source 169,as opposed to traditional software-based control schemes. Because thebattery pack voltage source 169 may output a variable voltage level(e.g., voltage lags from the plurality of battery cells 54), the fasterresponse time to voltage variations may enable the relay control circuit186 to control the hold mode 442 at a lower current level than thetraditional software control schemes. As such, the lower level ofcurrent during the hold mode 442 may allow the contactor 154 to consumeless energy than if the contactor 154 were to maintain the current levelof the pull-in mode 434.

Once the processor receives a signal that instructs the processor toopen the contactor 154, the processor may transition into a dischargemode 448. In the discharge mode 448, the processor may provide a lowsignal to the high-side enable input 187. As discussed previously, thelow signal applied to the high-side enable input 187 may result in thebattery pack voltage source 169 disengaging from the contactor 154 andthe current through the contactor 154 decreasing. During the dischargemode 448, the current may be reduced to the base current level 432.Further, discharging the coil of the contactor 154 may result in thecontactor 154 switching back to an open state. The contactor 154 mayremain in the discharge mode 448 until the processor 191 receives asignal to restart the pull-in mode 434.

Along with the relay control circuit 186 described above, FIG. 23 is aprocess flow diagram of a method 450 of controlling a contactor relayvia the relay control circuit 186. Initially, at block 452, theprocessor may select the pull-in mode 434. The pull-in mode 434, asdiscussed above, may function to switch the contactor 154 into a closedposition. Further, the pull-in mode 434 may enable the current flowingfrom the contactor 154 to reach a higher level than in the hold mode442. As illustrated in the plot 430 of FIG. 22 , a higher current may beneeded to pull-in the contactor 154 than to hold the contactor 154 inthe closed position.

Once the pull-in mode 434 is selected, the relay control circuit 186 mayapply the voltage from the battery pack voltage source 169 to thecontactor 154 at block 454. As described above with reference to FIG. 21, this may involve activating the transistor 192 and the power MOSFET196. The voltage output to the contactor 154 may increase the currentflowing through the contactor 154 until the current reaches the upperthreshold value 438 of the pull-in mode 434. As such, a determinationmay be made at each digital sample of the current flowing from thelow-side 199 of the contactor 154 as to whether the current is above thepull-in mode upper threshold 438 at block 456. If the digital sampleindicates that the current is not above the pull-in mode upper threshold438, the application of the voltage to the contactor 154 at block 454may continue and the determination at block 456 may be made again for asubsequent digital sample.

If the digital sample indicates, at block 456, that the current hasexceeded the pull-in mode upper threshold 438, then the relay controlcircuit 186 may disconnect the voltage from the battery pack voltagesource 169 to the contactor 154 at block 458. Disconnecting the voltageat block 458 may result in a reduction of the current flowing from thelow-side 199 of the contactor 154. Subsequently, at block 460, adetermination may be made as to whether the current has dropped belowthe pull-in mode lower threshold 440. If the current has not yet reachedthe pull-in mode lower threshold 440, then the voltage may remaindisconnected at block 458, and another determination at block 460 may bemade for a subsequent digital sample received by the processor.

On the other hand, if the determination at block 460 is that the currenthas fallen below the pull-in mode lower threshold 440, then adetermination may be made at block 462 as to whether a pre-set timelimit of the pull-in mode 434 has been reached. The time limit of thepull-in mode 434, as illustrated in the plot 430 of FIG. 22 , may beapproximately 200 ms in some embodiments. It should be noted that, thetime limit of the pull-in mode 434 may be set for any adequate time toswitch the contactor 154 to the closed position. If the determination atblock 462 is that the time limit of the pull-in mode 434 has not beenreached, then the voltage may be reapplied at block 454. Further, oncethe voltage is reapplied at block 454, a pull-in mode 434 portion of themethod 450, as described above, may be repeated until the time limit ofthe pull-in mode 434 has been reached at block 462.

Upon a determination, at block 462, that the time limit of the pull-inmode 434 has been reached, the processor may change instructions to therelay control circuit 186 from the pull-in mode 434 to the hold mode442. As discussed above, the hold mode 442 may maintain the contactor154 in the closed position, but it does not draw as much energy as thepull-in mode 434. A higher current may be beneficial to accomplishswitching during the pull-in mode 434 of the method 450, but maintainingclosure of the contactor 154 may be accomplished reliably at aconsiderably lower current during the hold mode 442. For example, asillustrated in FIG. 22 , the pull-in mode 434 may maintain a currentthrough the contactor 154 of approximately 400 mA, while the hold mode442 may maintain a current through the contactor 154 of approximately200 mA. This may not be possible with a software based controller, asused traditionally for contactor control, where the voltage is typicallyapplied to the contactor 154 similarly in both the pull-in mode 434 andthe hold mode 442. That is, a software based controller may apply avoltage to the high-side 197 of the contactor 154 to maintain a constantcurrent of 400 mA, rather than reducing the current to a hold mode levelafter a time limit for a pull-in mode is reached. The software basedcontroller may maintain the relatively high current through thecontactor 154 due to slow response times of the software basedcontroller due to looped timing. Because of the slow response time, thecurrent may need to be maintained at a relatively high level to providea buffer for the software to re-regulate the current during a voltagedip from a voltage source. The presently disclosed hardware based relaycontrol circuit 186, however, may respond quickly to any changes in thevoltage supplied by a voltage source. As such, a substantially lowercurrent level may be maintained with the hold mode 442 in the hardwarebased relay control circuit 186 because not as much time is necessary tore-regulate the current during a voltage dip from the battery packvoltage source 169.

Once the transition to the hold mode 442 is completed at block 464, thevoltage may remain disconnected until a determination is made at block466 as to whether the current has fallen below the hold mode lowerthreshold 444. If the current has yet to reach the hold mode lowerthreshold 444, the determination at block 466 may be repeated for eachdigital sample of the current flowing from the low-side 199 of thecontactor 154. When the current reaches the hold mode lower threshold444, the voltage may be reapplied to the contactor 154 at block 468 todrive the measured current from the low-side 199 of the contactor 154toward the hold mode upper threshold 446.

Subsequently, at block 470, a determination may be made as to whetherthe current has surpassed the hold mode upper threshold 446. If thecurrent has not reached the hold mode upper threshold 446, then thevoltage may remain applied to the contactor 154 at block 468 and thedetermination at block 470 may be made again for the next digital sampleof the current flowing from the low-side 199 of the contactor 154.Further, upon the determination at block 470 that the current is abovethe hold mode upper threshold 446, the voltage may be disconnected fromthe contactor 154 at block 472. Disconnecting the battery pack voltagesource 169 may result in the current flowing from the low-side 199 ofthe contactor 154 decreasing toward the hold mode lower threshold 444.Once the voltage is disconnected, a determination may be made at block474 as to whether a signal has been received at the processor 191 to endthe cycle. The signal may be an instruction to switch the contactor 154back to an open position. If the signal has not been received at theprocessor 191, the hold mode 442 portion of the method 450 may berepeated starting back at block 466 until the determination is made atblock 474 that the signal to end the cycle has been received at theprocessor. At this point, the cycle may end at block 476, and, becausethe voltage is not reapplied to the contactor 154, the current measuredat the low-side 199 of the contactor 154 may continue to decrease untilit reaches the current level 432 indicating that the contactor 154 isdischarged.

Bladed Fuse Connectors

As discussed briefly above, the fuse assembly 153 includes the fuse 156and two bladed fuse connectors 157 extending therefrom. The bladed fuseconnectors 157 may each include an S-shaped bend 210, as illustrated inFIG. 29 . The S-shaped bend 210 of each bladed fuse connectors 157 isdisposed between a first end 211 and a second end 212 of the bladed fuseconnector 157, as shown in the illustrated embodiment. As explainedbelow, the first ends 211 may be inserted into the high currentinterconnects 140 mounted on the PCB 136. When the fuse assembly 153 isinstalled in the battery module 22, the S-shaped bends 210 areconfigured to reduce the height of a top 213 of the fuse 156 relative tothe high current interconnects 140. In other words, the S-shaped bends210 enable the top 213 of the fuse 156 to be located closer to the PCB136 than a substantially flat or straight bladed fuse connector 157would. As shown in FIG. 30 , the bladed fuse connectors 157 are coupledto a lower portion of the fuse 156 relative to a fuse height 214 atconnecting points 215. As explained in detail below, the lower couplinglocation of the bladed fuse connectors 157 may reduce the overall heightof the fuse assembly 153 relative to the PCB 136.

The bladed fuse connectors 157 may be received into respective highcurrent interconnects 140 that are mounted on the PCB 136, asillustrated in FIG. 30 . The fuse assembly 153 may be specificallydimensioned to facilitate relatively compact packaging of the PCBassembly 58 and, thus, the overall battery module 22. For example, thefuse assembly 153 may be specifically constructed to have an overallheight dimension 216 that minimizes the height of the fuse assembly 153with respect to the PCB 136.

The bladed fuse connectors 157 may also be specifically dimensioned andshaped to reduce the overall height of the fuse assembly 153 withrespect to the PCB 136 when the bladed fuse connectors 157 are coupledwith the high current interconnects 140. In the illustrated embodiment,as described above, the bladed fuse connectors 157 extend outward fromthe fuse 156 along a lower portion of the fuse 156 relative to the fuseheight 214. As shown in FIG. 29 , the bladed fuse connectors 157 extendoutward in a substantially horizontal orientation (e.g., plus or minusten degrees) at the second end 212. However, in other embodiments thebladed fuse connectors 157 may have an angled or substantially verticalconnection with the fuse 156. S-shaped bends 210 within each of thebladed fuse connectors 157 then raise the height of respective portionsof the bladed fuse connectors 157, relative to the connection betweenthe bladed fuse connectors 157 and the fuse 156, so that the bladed fuseconnectors 157 can reach the openings 145 in the high currentinterconnects 140 without requiring the point at which the bladed fuseconnectors 157 couple with the fuse 156 to also extend above the highcurrent interconnects 140. In other words, the connecting point 215 ofthe bladed fuse connectors 157 may be lower (e.g., closer to the PCB136) than the openings 145 in the high current interconnects 140. Byincluding the S-shaped bends 210 in the bladed fuse connectors 157, thedistance 218 between the top 213 of the fuse 156 and the openings 145 inthe high current interconnects 140 may be reduced. For example, withoutthe S-shaped bends 210, the distance 218 would be greater, and as aresult the overall height 216 of the fuse assembly 153 relative to thePCB 136 would be increased. The bladed fuse connectors 157 enter theopenings 145 in a substantially vertical orientation (e.g., plus orminus ten degrees) at the first end 211. However, as mentioned above,other embodiments may have angled connections with the openings 145. TheS-shaped bends 210, in addition to reducing the height of the fuseassembly 153, may act as shock absorbers, enabling the fuse assembly 153to withstand vibrations of the vehicle 10 during operation, for example.

In the illustrated embodiment, the fuse 156 is elevated above the PCB136 by the bladed fuse connectors 157. However, in alternativeembodiments, the high current interconnects 140 may be disposed on thePCB 136 such that the fuse 156 sits on the PCB 136 or below the PCB 136.As mentioned above, the bladed fuse connectors 157 may be dimensioned toreduce the overall height of the fuse assembly 153. For example, theS-shaped bends 210 may be shaped so that a lower surface of the fuse 156and/or a connection point between the fuse 156 and the bladed fuseconnectors 157 is below an upper surface of the high currentinterconnect 140. In this manner, a relatively compact fuse assembly 153may be included in the battery module 22.

Battery Cell Interconnections

As mentioned above, the battery module 22 may include several batterycells 54 for storing and outputting the desired voltage from the batterymodule 22. More specifically, the battery cells 54 may be electricallyconnected or coupled to each other in series, parallel, or a combinationthereof to produce the desired output voltage (e.g., 48V). The batterycells 54 may include prismatic battery cells 54 with positive andnegative terminals extending therefrom, and bus bar cell interconnectmechanisms may be used to couple the positive terminal of one batterycell to the negative terminal of an adjacent battery cell. In someinstances, the term “adjacent” may be used to indicate that batterycells 54 or other battery module components are deposited beside oneanother. For example, terminals of two battery cells 54 deposited sideby side may be referred to as adjacent terminals. Additionally, the term“adjacent” may be used to indicate that battery cells 54 or othercomponents are in contact with one another. Furthermore, the term“adjacent” may include directly adjacent and immediately adjacent.

FIG. 31 illustrates an interconnect assembly 220 that may be presentwithin the battery module 22 to facilitate connections between thebattery cells 54 themselves as well as connections between the batterycells 54 and the PCB 136. As described in detail below, the interconnectassembly 220 may include bus bar cell interconnects 222 and adapters234. The interconnect assembly 220 may include bus bar cellinterconnects 222 including loops 224 that are generally serpentine witha body that would be generated by a loop orbiting about a line whileundergoing translation along the line. The bus bar cell interconnects222 may also include flat end portions on each end of the loop 224.These loops 224, in some embodiments, may all be made from the samematerial (e.g., copper). Specifically, the loops 224 may be copper busbars that are bent into a serpentine curled shape. That is, the loop 224and the flat end portions may all be made from the same material. A holemay be formed in one flat end portion of each bus bar cell interconnect222 for coupling with one of two adjacent battery cells 54. The hole maybe adapted to receive a terminal 230. In the illustrated embodiment, andas discussed in detail below with reference to FIG. 35 , the bus barcell interconnects 222 may include the loop 224 between a first end 240(e.g., plate contact end) and a second end 242 (e.g., terminal matingend). For example, the first and second ends may be generally horizontalor flat compared to the loop 224. In addition, an upper portion of theloop 224 approximately halfway between the first and second ends may bea generally horizontal or flat portion. Still further, the loops 224 mayinclude an engagement feature 225 for coupling to a complementaryengagement feature (or mounting feature) of the lid assembly 56. In theillustrated embodiment, the engagement feature 225 is a hole formed inthe generally flat portion of the loop 224 between the first and secondends. This generally flat portion of the loop 224 may enable relativelyeasy machining of the engagement feature 225 into the loop 224, asopposed to machining the engagement feature 225 into an arced portion ofthe loop 224. In addition, the generally flat portion may be arelatively easy portion of the loop 224 for pick and place machinery togrip the loop 224 and to place the loop 224 onto the complementaryengagement feature of the lid. In some embodiments, the engagementfeature 225 may receive or be mounted on a pin coupled to the lidassembly 56. However, in other embodiments, the cover 52 may include thecomplementary engagement or mounting feature.

During assembly of the battery module 22, the loops 224 may bepositioned on the battery cells 54, and the PCB assembly 58 may belowered onto the interconnected battery cells 54. As shown in theillustrated embodiment, the PCB assembly 58 may be equipped with voltagesense connection tabs 226 disposed along the edges of and coupled to thePCB 136. That is, one end of the voltage sense connect tab 226 ismounted on a plane of the PCB 136, while an opposite end extends awayfrom the PCB 136. These voltage sense connection tabs 226 may bepositioned on the PCB 136 such that, when the PCB assembly 58 is loweredonto the interconnected battery cells 54, the voltage sense connectiontabs 226 land on an end of the loops 224, or other type of bus bar cellinterconnect 222. More specifically, with respect to the embodimentillustrated in FIG. 31 , the voltage sense connection tabs 226 may becoupled to the PCB 136 at positions that will be aligned with flattenedportions of the bus bar cell interconnects 222 when the PCB assembly 58is disposed over the battery cells 54.

As shown in FIG. 31 , the voltage sense connection tabs 226 may includean arced portion between the PCB 136 and the bus bar cell interconnects222. In the illustrated embodiment, the arced portion extends in anupward direction between two substantially flat ends 221 and 223. Theflat ends 221 and 223 may be substantially parallel to one another. Forexample, in the illustrated embodiment the flat end 223 is mounted onand substantially horizontal with respect to the plane of the PCB 136.The flat ends 221 and 223 enable a greater contact surface for couplingthe voltage sense connection tabs 226 to the PCB 136 and bus bar cellinterconnects 222. As shown in the illustrated embodiment, the archedportion biases the flat ends 221 and 223 in a downward direction. Forexample, when the flat end 221 is mounted on the PCB 136, the arcedportion biases the flat end 223 toward the bus bar cell interconnect222. Moreover, in the illustrated embodiment, the flat end 223 and thearced portion extend laterally off of the PCB 136. That is, the arcedportion and flat end 223 extend away from the PCB 136 off of the side ofthe PCB 136. In other words, the arced portion and flat end 223 areessentially cantilevered from the PCB 136 via a connection establishedby coupling features extending from the flat end 221 and engaging thePCB 136.

The voltage sense connection tabs 226 may also include a slit 227 formedalong the arced portion between the connection to the PCB 136 and thebus bar cell interconnects 222. The slit 227 essentially splits at leastthe arced portion of the voltage sense connection tab 226 into twoportions. The slit 227 may reduce the overall weight of the voltagesense connection tabs 226 by removing material while maintaining both anelectrical and mechanical connection to the PCB 136 and bus bar cellinterconnects 222. Additionally, the slit 227 may provide greaterflexibility to the arced portion of the voltage sense connection tabs226. As a result, the voltage sense connection tabs 226 may adjust toand absorb shocks caused by vibrations and movements within the vehicle10.

The voltage sense connection tabs 226 may be welded to the bus bar cellinterconnects 222 to complete the connection. For example, in theillustrated embodiment, the end 223 of the voltage sense connection tab226 is welded to the plate contact end of the bus bar cell interconnect222. When coupled to the bus bar cell interconnects 222, the voltagesense connection tabs 226 function as a voltage sense lead for voltagesensors on the PCB 136. The voltage sense connection tabs 226 may besoldered into electrical communication with the voltage sensors on thePCB 136 prior to the PCB assembly 58 being positioned on the batterycells 54. By using voltage sense connection tabs 226 integrated onto thePCB 136 in conjunction with the cell interconnect loops 224, theillustrated embodiment eliminates the need for a separate bus for makingthe voltage sense connections. This may facilitate a relatively simpleand inexpensive assembly of the battery module 22, in addition toreducing the space requirement for voltage sensing components within thebattery module 22. It is appreciated that, while the voltage senseconnection tabs 226 have been discussed in reference to bus bar cellinterconnects 222 including loops 224, that the voltage sense connectiontabs 226 may be utilized with other types of bus bar cell interconnects222. For example, the voltage sense connection tabs 226 may couple tobus bar links 260 (described in detail below) to relay a voltage fromthe battery cells 54.

In another embodiment, the voltage sense connection tabs 226 each mayinclude a twisted section 228 that extends from a plateaued portion ofthe arced portion, as shown in FIG. 32 . The twisted section 228 mayinclude a C-shaped or serpentine curvature that inverts a surface of thevoltage sense connection tab 226 from an upward facing orientation atthe connection to the PCB 136 to a downward facing orientation at theconnection to the bus bar cell interconnect 222. Additionally, thetwisted section 228 is oriented substantially perpendicular to the end223 of the voltage sense connection tab 226. In either of theembodiments illustrated in FIGS. 31 and 32 , the voltage senseconnection tabs 226 may include coupling features 229, such as legs, tofacilitate connection of the voltage sense connection tab 226 to the PCB136. In some embodiments, the coupling features 229 may couple to thevoltage sense components on the PCB 136. In other embodiments, thecoupling features 229 may mount the voltage sense connection tab 226 tothe PCB 136 so that a flattened portion of the voltage sense connectiontab 226 is held in contact with a voltage sensing lead disposed on anouter surface of the PCB 136. While not shown in the illustratedembodiment of FIG. 32 , any of various portions of the voltage senseconnection tab 226, including the twisted section 228, may incorporate aslit, such as the slit 227, to improve flexibility, conserve material,and so forth.

As described above, the battery module 22 may include voltage sensingcomponents to couple the bus bar cell interconnects 222 to the PCB 136in order to relay a voltage from the battery cells 54. In anotherembodiment, the voltage sense connection tab 226 may include a wirebonded connection 233, as shown in FIG. 33 . The wire bonded connection233 may include a wire, a ribbon of metal, electric trace, or otherconductive material coupled between the PCB 136 and bus bar cellinterconnects 222. For example, the wire bonded connection 233 may bemade of metals such as copper, aluminum, tin, or the like. In someembodiments, the wire bonded connection 233 may be welded between thebus bar cell interconnect 222 and a PCB mounted body portion 231 of thevoltage sense connection tab 226. The wire bonded connection 233 may becurved or arced to follow the profile of the PCB 136 and the bus barcell interconnects 222. For example, the wire bonded connection 233 maybe angled in a downward direction in embodiments where the PCB 136 ismounted above the bus bar cell interconnects 222. The wire bondedconnection 233 enables a streamlined and robust electrical connectionbetween the bus bar cell interconnects 222 and the PCB 136.Additionally, as with previously disclosed embodiments, the wire bondedconnection 233 may be vibration tolerant and capable of absorbing shocksand the like while maintaining the electrical connection between the busbar cell interconnects 222 and the PCB 136. Furthermore, the wire bondedconnection 233 is relatively space efficient within the battery module22.

As mentioned above, the wire bonded connection 233 may be made of avariety of conductive materials. In some embodiments, the wire bondedconnection 233 is aluminum. However, the bus bar cell interconnect 222may be copper. To facilitate the connection between dissimilar metals,the bus bar cell interconnect 222 may have a piece of the dissimilarmetal attached to it (e.g., via soldering). Therefore, in someembodiments, a copper bus bar cell interconnect 222 has a piece ofaluminum attached to the bus bar cell interconnect 222 (e.g., duringpreassembly) to facilitate the connection of the wire bonded connection233. In other words, additional conductive materials (e.g., metals) maybe added to the bus bar cell interconnects 222 to account for thematerial used for the wire bonded connections 233.

The wire bonded connection 233 of the voltage sense connection tab 226may facilitate a relatively simple and inexpensive assembly of thebattery module 22. For example, the body portion 231 of the voltagesense connection tab 226 may be mounted to the PCB 136 using thecoupling features 229 as described above with reference to FIG. 32 .Then, a first end of the wire that forms the wire bonded connection 233may be welded to the bus bar cell interconnect 222. The first end of thewire bonded connection 233 may be part of a continuous spool ofconductive wire. After the first end of the wire bonded connection 233is welded to the bus bar cell interconnect 222, a length of wire may beunspooled, or otherwise disposed between the welded first end of thewire bonded connection 233 and the body portion 231 of the voltage senseconnection tab 226. A second end of the wire bonded connection 233 maybe welded to the body portion of the voltage sense connection tab 226 tocomplete the electrical connection between the bus bar cell interconnect222 and the PCB 136. The wire may be cut after welding the second end tothe body portion of the voltage sense connection tab 226. In thismanner, connections between each of the plurality of bus bar cellinterconnects 222 and the PCB 136 may be made efficiently and usingrelatively few materials. However, in other embodiments, the wire bondedconnection 233 may be connected between the voltage sense connection tab226 and the bus bar cell interconnect 222 in the reverse order ordifferent order entirely. For example, the first end of the wire thatforms the wire bonded connection 233 may be welded to the voltage senseconnection tab 226 before the second end of the wire is welded to thebus bar cell interconnect 222. Moreover, as mentioned above, the wirebonded connection 233 may be utilized with other styles of bus bar cellinterconnects 222, such as bus bar links 260 (described below).

As discussed above, FIG. 31 illustrates an interconnect assembly 220that may be present within the battery module 22 to facilitateconnections between the battery cells 54 themselves as well asconnections between the battery cells 54 and the PCB 136. As describedin detail below, the interconnect assembly 220 may include bus bar cellinterconnects 222 and adapters 234. The interconnect assembly 220 mayinclude bus bar cell interconnects 222 including loops 224 that aregenerally serpentine with a body that would be generated by a looporbiting about a line while undergoing translation along the line. Thebus bar cell interconnects 222 may also include flat end portions oneach end of the loop 224. These loops 224, in some embodiments, may allbe made from the same material (e.g., copper). Specifically, the loops224 may be copper bus bars that are bent into a serpentine curled shape.That is, the loop 224 and the flat end portions may all be made from thesame material. A hole may be formed in one flat end portion of each busbar cell interconnect 222 for coupling with one of two adjacent batterycells 54. The hole may be adapted to receive a terminal 230. In theillustrated embodiment, and as discussed in detail below with referenceto FIG. 34 , the bus bar cell interconnects 222 may include the loop 224between a first end 240 (e.g., plate contact end) and a second end 242(e.g., terminal mating end). For example, the first and second ends maybe generally horizontal or flat compared to the loop 224. In addition,an upper portion of the loop 224 approximately halfway between the firstand second ends may be a generally horizontal or flat portion. Stillfurther, the loops 224 may include an engagement feature 225 forcoupling to a complementary engagement feature (or mounting feature) ofthe lid assembly 56. In the illustrated embodiment, the engagementfeature 225 is a hole formed in the generally flat portion of the loop224 between the first and second ends. This generally flat portion ofthe loop 224 may enable relatively easy machining of the engagementfeature 225 into the loop 224, as opposed to machining the engagementfeature 225 into an arced portion of the loop 224. In addition, thegenerally flat portion may be a relatively easy portion of the loop 224for pick and place machinery to grip the loop 224 and to place the loop224 onto the complementary engagement feature of the lid. In someembodiments, the engagement feature 225 may receive or be mounted on apin coupled to the lid assembly 56. However, in other embodiments, thecover 52 may include the complementary engagement or mounting feature.

During assembly of the battery module 22, the loops 224 may bepositioned on the battery cells 54, and the PCB assembly 58 may belowered onto the interconnected battery cells 54. As shown in FIG. 31 ,the PCB assembly 58 may be equipped with voltage sense connection tabs226 disposed along the edges of and coupled to the PCB 136. Thesevoltage sense connection tabs 226 may be positioned on the PCB 136 suchthat, when the PCB assembly 58 is lowered onto the interconnectedbattery cells 54, the voltage sense connection tabs 226 land on thefirst end 240 of the bus bar cell interconnects 222 described above. Thevoltage sense connection tabs 226 may then be welded to the bus bar cellinterconnects 222 to complete the connection. The voltage senseconnection tabs 226 function as a voltage sense lead for voltage sensorson the PCB 136, and the voltage sense connection tabs 226 are solderedinto electrical communication with the voltage sensors on the PCB 136prior to the PCB assembly 58 being positioned on the battery cells 54.By using voltage sense connection tabs 226 integrated onto the PCB 136in conjunction with bus bar cell interconnects 222, the illustratedembodiments eliminate the need for a separate bus for making the voltagesense connections. This may facilitate a relatively simple andinexpensive assembly of the battery module 22, in addition to reducingthe space requirement within the battery module 22.

FIG. 34 is an exploded view of four battery cells 54 being electricallycoupled together via the interconnect assembly 220 of FIG. 31 . Asdescribed above, the interconnect assembly 220 may include the bus barcell interconnect 222 and the adapter 234. In the illustratedembodiment, each of the battery cells 54 includes two oppositely chargedterminals 230 and 232. One of these terminals functions as the anode ofthe particular battery cell 54, while the other functions as thecathode. As noted above, the battery cells 54 may be arranged so thatthey are electrically coupled in series. For example, the anode of onebattery cell 54 is disposed immediately adjacent the cathode of aneighboring battery cell 54 with respect to the aligned series ofbattery cells 54 and they are communicatively coupled. As discussedabove, “immediately adjacent” may refer to the terminals 230 and 232being side by side within the context of the arrangement of theplurality of the terminals 230 and 232.

In some embodiments, the oppositely charged terminals 230 and 232 of thebattery cells 54 may be made from different materials (e.g., copper andaluminum). In such instances, the interconnect assembly 220 may includeadapters 234 for transitioning between these two materials. In theillustrated embodiment, for example, the adapters 234 are configured toform a link between the aluminum posts (e.g., terminals 232) of thebattery cells 54 and the copper bus bar cell interconnects 222. Eachadapter 234 may include a contact surface that transitions from aluminumat one end 236 to copper at the opposite end 238. For example, the oneend 236 may include an aperture that receives the aluminum post 232.Additionally, the opposite end 238 may be electrically coupled to theone end 236. Thus, the bus bar cell interconnects 222 may couple to acopper connection at the opposite end 238 and forgo a dissimilar metalconnection. The aluminum end 236 of the adapter 234 is configured to bepositioned over the terminals 232, as shown, and the copper end 238 ofthe adapter 234 is designed to receive the first end 240 of theinterconnect 222. For example, in the illustrated embodiment, the firstend 240 of the interconnect 222 is aligned with and disposed over thecopper end 238 to communicatively couple the bus bar cell interconnect222 to the battery cell 54. However, the second end 242 of theinterconnect 222 receives the terminal 230 of the adjacent battery cell54 to complete the connection. As described above, the adapter 234 mayfacilitate a single metal connection between the battery cells 54. Itshould be noted that embodiments in accordance with the presentdisclosure also include reverse configurations, wherein copper andaluminum are switched with respect to the ends 236 and 238.

The illustrated bus bar cell interconnect 222, as described above,includes the plate contact end 240 that may be welded onto the copperend 238 of the corresponding adapter 234. At an opposite end of the loop224 from the plate contact end 240, the bus bar cell interconnect 222includes the terminal mating end 242 designed to fit over the copperterminal 230 and to establish an electrical engagement between the cellinterconnect 222 and the copper terminal 230. The terminal mating end242 may include a collar on the bottom surface. In alternativeembodiments, the collar may be on the top surface of the terminal matingend 242 or on both surfaces. The collar may, for example, provide extrasurface area for deposition of weld metal. As illustrated, the loop 224is shaped in a specific serpentine or curled geometric form. Any stress,vibrations, motion, or other disturbances encountered by the batterymodule 22 may be distributed or dampened over this serpentine or curledgeometric form, without weakening any welds. In this way, the loops 224may enable a longer lifetime of the cell interconnect assembly 220 thanwould be possible with, for example, rigid bus bars welded between theterminals 230 and 232.

The bus bar cell interconnects 222 may take on other shapes that promotedistribution of forces and motion due to vibrations and otherdisturbances. FIG. 35 shows one such embodiment, where the bus barinterconnect 222 includes a “hair-pin” shaped bus bar 250. The term“hair-pin” may refer to any shape that includes two flat contactsurfaces 252 and a raised, curved portion 254 (e.g., a raised arch)leading from one contact surface 252 to the other. Similar to the loop224 described above, one of the contact surface 252 of the hair-pin busbar 250 may be welded to the copper end 238 of the adapter 234 locatedon the aluminum post, while the opposite contact surface 252 is weldedto the terminal 230. Other relatively curved or bent shapes of the busbar interconnects 222 may be used in other embodiments.

In some embodiments, the bus bar cell interconnect 222 may be configuredto transition between the two materials (e.g., aluminum and copper)without the use of an additional adapter (e.g., adapter 234) orfastener. FIG. 36 illustrates a bus bar link 260 (e.g., bus bar, bus barcell interconnect, link) that may perform this function. The link 260 isa single piece component made from two different materials. In theillustrated embodiment, for example, the link 260 includes a copperportion 262 for interfacing with the copper terminal 230 and an aluminumportion 264 for interfacing with the aluminum terminal 232. The initialconstruction of the link 260 may involve finger jointing, as shown by ajoint 265, and rolling the copper portion 262 and the aluminum portion264 together to form the single piece link made from the two separatematerials. The link 260 includes two curved portions 266, one configuredto slope toward each of the battery terminals 230 and 232. The curvedportions 266 provide additional surface area for welding the terminals230 and 232 to the link 260, as compared to a thinner link that extendsstraight across both terminals 230 and 232. In certain embodiments, thecurved portions 266 may be formed into the link 260 through a flangedstamping process, although other techniques may be used to achieve asimilar shape. Overall, the link 260 may provide a more structuralconnection between the battery terminals 230 and 232 than would beavailable through the more flexible loop or hair-pin embodiments,without the added height or the additional adapter 234.

In other embodiments, the link 260 may include a different shape ororientation relative to the battery terminals 230 and 232. For example,as shown in FIGS. 37 and 38 , the link 260 may include a body portion270 that is generally rectangular with rounded corners and a constantthickness 269. However, in other embodiments, the body portion 270 maybe an oval, a parallelogram, a triangle or the like depending on theconfiguration of the battery cells 54. In addition, the body portion 270of the link 260 shown in the illustrated embodiment is asymmetrical.That is, one rounded corner 271 of the rectangular body portion 270 hasa greater radius than the remaining rounded corners. The rounded corner271 serves as an indication of the orientation of the bus bar link 260.For example, this indication may be present on the copper portion 262and not on the aluminum portion 264, or vice versa. It should be notedthat, in other embodiments, other indications such as cut outs, raisedportions, keying features, and the like may be utilized. As a result,the copper portion 262 and the aluminum portion 264 may be readilyidentified during installation. Therefore, during installation thelikelihood of installing the bus bar cell interconnects 222 on theincorrect terminals (e.g., the copper portion 262 on the aluminumterminal 232 and the aluminum portion 264 on the copper terminal 230)may be reduced because the correct alignment is readily identifiable.

A lower surface 272 of the link 260, as illustrated in FIG. 38 , mayinclude collars 273 (e.g., similar to the curved portions 266 of FIG. 36) surrounding apertures 274 in the body portion 270. The collars 273extend in a direction substantially perpendicular to a plane of thelower surface 272. In other words, the collars 273 are raised orelongated relative to the lower surface 272. This shape enables thecollars 273 to receive and surround the terminals 230 and 232 wheninstalled on the battery cells 54. In some embodiments, the collars 273are thicker than the body portion 270. As shown, an inner circumference275 and an outer circumference 276 of the collars 273 are substantiallyconstant along the extended length of the collars 273. In other words,in the illustrated embodiment, the collars 273 are generally cylindricaland not tapered. However, in other embodiments, the collars 273 may betapered in order to apply a compressive force to the battery terminals230 and 232 when disposed over the terminals. The collars 273 may bestamped or pressed into the body portion 270 to form the integral link260. However, in other embodiments, the collars 273 may be press fitinto the apertures 274, welded, machined, or otherwise formed along thebody portion 270 of the link 260.

As mentioned above, the body portion 270 of the link 260 may include twodifferent materials (e.g., aluminum and copper). The copper portion 262and the aluminum portion 264 may meet at the joint 265. The joint 265mechanically and electrically couples the copper portion 262 and thealuminum portion 264. In some embodiments, the body portion 270 may befinger jointed and rolled to establish a mechanical and electricalconnection between the copper portion 262 and the aluminum portion 264.More specifically, a plurality of layers of copper and aluminum may bestacked in an alternating sequence at the joint 265. Then, compressivepressure may be applied to the joint 265 to provide a gas tight sealbetween the alternating layers. In other words, the pressure of therolling process substantially joins the copper portion 262 to thealuminum portion 264 without the use of an alternative mechanicaljoining process, such as welding. Moreover, the gas tight seal generatedby the rolling process may reduce or eliminate the need for an insulatoraround the joint 265 to impede galvanic corrosion of the joint 265.

As discussed above, the link 260 may be coupled to adjacent batterycells 54 to electrically couple the battery cells 54. Again, thealuminum portion 264 may be coupled to the aluminum terminal 232 of onecell and the copper portion 262 may be coupled to the aluminum terminal230 of an adjacent cell. In some embodiments, a weld may form theconnection between the link 260 and the terminals 230 and 232. Asillustrated in FIG. 39 , the weld may be made from a top surface 277 ofthe body portion 270. Moreover, the welds may be aligned with thecollars 273 such that they do not extend beyond the collars 273. Thatis, the weld area may be contained within the outer circumference 276 ofthe collar 273 and the weld may be the same width as the outercircumference 276 of the collar 273. Because the collars 273 are thickerthan the body portion 270, the weld may penetrate a distanceapproximately equal to the full thickness 269 of the body portion 270without burning through the collar 273. In other words, the collars 273extend away from the body portion 270 in the direction of the weld(i.e., toward the terminals 230 and 232). As a result, a strong weld maybe achieved due to the increased weld area between the collars 273 andthe terminals 230 and 232. Moreover, the link 260 may reduce lateralforces on the terminals 230 and 232 resulting from swelling or vibrationof the battery cells 54. In other embodiments, the weld may onlypartially penetrate the thickness 269 of the body portion 270 or may beformed entirely on the top surface 277.

A perspective view of the link 260 coupled to the battery terminals 230and 232 is shown in FIG. 39 . As shown, the link 260 is coupled to anupper portion of the terminals 230 and 232. However, as described indetail below, the link 260 (or other type of bus bar interconnect 222)may be supported on the lid assembly 56, which is not shown in FIG. 39 .The terminals 230 and 232 may extend through the lid 290 to be coupledwith the bus bar interconnects 222 disposed on a lid of the lid assembly56. As mentioned below, the lid may feature an asymmetrical indentationto support the asymmetrical shape of the bus bar interconnects 222.

Lid Assembly and Method of Manufacture

The bus bar cell interconnects 222 described at length above may form aportion of the lid assembly 56 introduced above with reference to FIG. 6. In addition to these components, the lid assembly 56 may include anynumber of desirable components that are mounted to or integral with alid 290. A top view of one embodiment of the lid 290 is provided in FIG.40 . As illustrated, the lid 290 may be configured to interface with thebattery cells 54. For example, the lid 290 may include apertures 292through which the battery terminals 230 and 232 of the battery cells 54extend. In addition, the lid 290 may include fingers 294 (e.g., flexiblefingers) aligned with the battery cells 54 and used to hold down thebattery cells 54, as described in detail below. In the illustratedembodiment, some fingers 294 of the lid 290 are equipped with mountedtemperature sensors 296. The lid 290 may also include a built-in ventchamber 298 used to channel vented gases out of the battery module 22,these gases being vented from one or more battery cells 54. The lid 290may be molded or cutout from plastic, glass-filled polymer, or any otherappropriate material.

As mentioned above, the lid 290 may be used for mounting sensors, suchas temperature sensors 296 near the battery cells 54. Such temperaturesensors 296 may be coupled to the PCB 136 in order to provide relativelyaccurate temperature monitoring of the battery cells 54. Themeasurements collected via the temperature sensors 296 may be used incontrolling operation of the battery module 22. For example, the batterymodule 22 may include an active cooling system that may be activated oradjusted in response to a high sensed temperature of the battery cells54. In other embodiments, the PCB assembly 58 may output an alert to acontrol system of the vehicle 10 when the battery cells 54 reach anundesirable high temperature. The lid 290 may allow for thesetemperature sensors 296 (and other sensors) to be disposed in closeproximity to the battery cells 54 while still being coupled to the PCB136. In the illustrated embodiment, the temperature sensors 296 aredisposed on two fingers 294 of the lid 290, and these two fingers 294correspond to different battery cells 54 of the battery module 22. Inother embodiments, however, there may be any desirable number oftemperature sensors 296 mounted to any number of fingers 294 on the lid290. It may be desirable, in some embodiments, to mount the temperaturesensors 296 on fingers 294 of the lid 290 disposed adjacent particularbattery cells 54 that are expected to heat up the most during operationof the battery module 22. However, other arrangements and numbers oftemperature sensors 296 (or other sensors) may be possible as well.

It should be noted that in addition to interfacing with the batterycells 54, the lid 290 is also configured to receive and hold componentsof the PCB assembly 58 thereon. For example, in the illustratedembodiment, the lid 290 includes a cavity 300 for supporting thecontactor 154. Other features of the lid 290 may mate with and carryvarious components of the PCB assembly 58, as discussed at length below.Further, the lid 290 may be equipped with slots 302 for interfacing withthe corresponding clips 114 of the lower housing 50.

As noted above, the fingers 294 of the lid 290 may be used to hold downthe battery cells 54 over which the lid 290 is layered. An example ofthe fingers 294 performing this function is illustrated in FIG. 41 . Thebattery cells 54, which are stacked relative to each other, may not allbe constructed to exactly the same dimensions. For example, in someembodiments, the battery cells 54 may vary slightly in height, such thatthe lid 290, if it were particularly rigid, would sit upon the batterycells 54 just enough to rest atop the tallest battery cell 54. Thiscould potentially waste space within the battery module 22 and lead toweaker connections between the lid 290 and the battery cells 54. Theillustrated lid 290, however, includes the fingers 294, and thesefingers 294 extend downward at an angle toward the battery cells 54(e.g., relative to a top surface of the lid 290). It should be notedthat one of ordinary skill in the art would recognize that the topsurface (e.g., as described above relative to the angles at which thefingers 294 extend downwardly from the lid 290) may refer to a generallyplanar reference surface extending over a top of the lid 290 generallylevel with, e.g., the apertures 292 (e.g., disposed in rows) illustratedin FIGS. 40-43 .

The fingers 294, as shown in FIGS. 41-43 , may be portions of the lid290 that are cut out and/or allowed to flex relative to the rest of thelid structure via a hinge 291 (e.g., living hinge). In other words, eachof the fingers 294 may be cantilevered from a connection point within anopening in the lid 290, where said connection point, in someembodiments, may include the hinge 291. The fingers 294 may be angleddownward initially and, once placed in contact with the battery cells54, may exert a slight force (e.g., downward force F) to hold down thebattery cells 54 within the lower housing 50. In some embodiments, eachfinger 294 may be disposed on a respective hinge 291 (e.g., as describedabove) that includes a respective spring 293, where the respectivespring 293 is configured to transfer a spring force through the finger294 and as a downward force F onto the battery cell 54 corresponding tothe finger 294. Specifically, the spring 293 disposed around the hinge291 may bias the flexible finger 294 at the downward angle in order toapply a compressive force (e.g., downward force F) to the correspondingbattery cell 54 when the finger 294 is brought into contact with thebattery cell 54. In other embodiments, the hinge 291 itself may transfera force through the finger 294 onto the corresponding battery cell 54.The fingers 294 may accommodate variances in height of the assembledbattery cells 54, such that all of the battery cells 54 may be held inplace between the lid 290 and the lower housing 50, regardless of theheights of the battery cells 54.

Additionally, the height of each battery cell 54 may determine the angleits respective finger 294 extends downwardly when the lid 290 isdisposed over the battery cells 54. For example, downward angles 295 ofthe fingers 294 extending from the upper surface of the lid 290 maydecrease as the lid 290 is lowered onto the battery cells 54 to hold thebattery cells 54 in place. Specifically, the fingers 294 elasticallydeform by bending along the hinge 291, as discussed above, therebydecreasing the angle 295. The downward angle 295 of one of the fingers294 may decrease more when placed against a taller battery cell 54 thanit would when placed over a shorter battery cell 54. Accordingly, theangles 295 of some of the fingers 294 may decrease by a different amountthan some of the other fingers 294, in order to accommodate the heightof the battery cells 54.

In addition, the height of each battery cell 54 may determine thedownward force its respective finger 294 exerts on the battery cell 54.For example, each of the fingers 294 exert some amount of downward forceF onto the battery cells 54 to hold the battery cells 54 in place.Specifically, the hinge 291, or a spring 293 associated with the hinge291, may transfer a force from the finger 294 to its correspondingbattery cell 54. The downward force F may be greater when applied to ataller battery cell 54 as opposed to a shorter battery cell 54, since ataller battery cell 54 bends the finger 294 and/or compresses the spring293 by a greater amount. Accordingly, the downward force F may bedifferent for different fingers 294 of the lid 290, in order toaccommodate the height of the battery cells 54.

There may be several different possible arrangements of the fingers 294on different embodiments of the lid 290. In the illustrated embodiment,the fingers 294 are placed symmetrically on either side of thecorresponding battery cells 54. The pads of the fingers 294 may rest onpositions of an upper surface 310 of the battery cell 54 located betweenthe respective battery terminals 230 and 232 and a centrally locatedvent 312 of the battery cell 54. More specifically, in the illustratedembodiment, the fingers 294 are configured to contact the upper surface310 of the battery cell 54 between a fill hole 314 of the battery cell54 and the vent 312. It should be noted that, in other embodiments, thefingers 294 may be disposed in different positions and orientationsrelative to the upper surface 310 of the battery cells 54.

Besides interacting with the battery cells 54, the lid 290 may beconfigured to receive and hold other components (e.g., PCB components)throughout operation of the battery module 22. In some embodiments, thelid 290 may be pre-loaded with these components prior to a finallayering of the different assemblies of the battery module 22. FIG. 30shows certain parts of the lid 290 that may facilitate such pre-loadingand other connections to the PCB assembly 58. As mentioned above, thelid 290 may include the cavity 300 for receiving and holding thecontactor 154. In addition to the cavity 300, the lid 290 may includeclips 330 for securing a top end of the contactor 154 placed within thecavity 300. In addition, the illustrated lid 290 includes extensions 332designed to fit through corresponding openings within the PCB 136 formating the PCB 136 with the lid 290.

The lid 290 may further include features for interacting with the busbar interconnects 222. For example, in the illustrated embodiment, thelid 290 includes walls 334 built between every other pair of apertures292 formed in the lid 290. In other words, a pattern may be achieved oftwo apertures 292, one wall 334, two apertures 292, one wall 334, etc.These walls 334 may thus be positioned, when the lid assembly 56 isfully assembled, between subsequent bus bar interconnects 222 connectingthe battery cells 54. Thus, the walls 334 may prevent or reduce alikelihood of internal shorts between the bus bar interconnects 222within the battery module 22. For example, the walls 334 may preventloose material from causing a short during assembly.

Further, as illustrated in FIGS. 28 and 30 , each aperture 292 may besurrounded by an indentation 335. The indentations 335 may be includedto accommodate the bus bar interconnects 222 and facilitate efficientand accurate assembly and inspection of the lid 290. For example, theloops 224 (e.g., as shown in FIG. 25 ) may include the plate contact end240 and the terminal mating end 242. The ends 240, 242 of the loops 224may each fit into one of the indentations 335 surrounding the apertures292. Further, in the embodiment shown in FIG. 28 , every otherindentation 335 includes an angled edge 336. The indentation 335 withthe angled edge 336 may be configured to receive the terminal mating end242 of the loop 224, and the indentation 335 without the angled edge 336may be configured to receive the plate contact end 240 of the loop 224.In this way, embodiments where some (e.g., half) of the terminals 232are aluminum or some other non-copper metal, the aluminum terminals 232may extend through the apertures 292 with surrounding indentations 335that do not have the angled edge 336, and corresponding adapters 234 maybe placed over each aluminum terminal 232 extending through the aperture292 without the angled edge 336 indentation 335. The plate contact end240 of the loop 224 may contact the copper end 238 of the adapter 234.This may assist in ensuring that adapters 234 are placed over the properterminals 232. In other words, the indentations 335 may serve toaccommodate the bus bar interconnects 222, to accommodate the adapters234, and to offer a visual cue for assembly and inspection of the lid290. In other embodiments (e.g., embodiments including a straight busbar interconnect 222), one indentation 335 may span over two apertures292 (e.g., two apertures 292 between a pair of two walls 334), and thestraight bus bar interconnect 222 may fit into the single indentation335. In other words, the indentations 335 may be oriented perpendicularto the orientation shown in FIG. 28 , or in some other orientation, suchthat the indentations 335 accommodate the specific geometry and/ororientation of the bus bar interconnects 222 associated with theembodiment.

In other embodiments (e.g., as illustrated in FIG. 30 ), the lid 290 mayalso be equipped with posts or walls (e.g., mounting features 337) uponwhich the bus bar interconnects 222 (e.g., loops 224) may be pre-loadedduring assembly. These features 337 could extend outward from positionsbetween the illustrated walls 334 or apertures 292. For example, the lid290 may include the walls 334 for preventing internal shorts disposedadjacent to and between posts (e.g., mounting features 337) configuredto hold the bus bar interconnects 222 (e.g., loops 224) in a particularposition relative to the lid 290. This may result, for example, in apattern of one aperture 292, one mounting feature 337, one aperture 292,one wall 334, one aperture 292, one mounting feature 337, one aperture292, one wall 334, and so on and so forth. The loops 224 may includeopenings (e.g., engagement feature 225) disposed at an upper portion forbeing coupled to a post (e.g., mounting feature 337) extending from thelid 290, as discussed above with reference to FIG. 25 .

In other embodiments, the bus bar interconnects 222 may include thehair-pin design 250, and the lid 290 may be equipped with wallsextending upward for the hair-pins 250 to be draped over. In someembodiments, any such features of the lid 290 may facilitate mounting ofthe desired bus bar interconnects 222 in a specific orientation relativeto their position within the battery module 22. For example, thefeatures may be oriented in a first direction on one side of the batterymodule 22 and oriented in a second direction on the opposite side of thebattery module 22. Other arrangements and features may be included inthe lid 290 in addition to or in lieu of those described above.Additionally, the walls 334 and/or the extensions 332 may be integral(e.g., integrated) with the lid 290. Further, the lid 290, the walls334, the extensions 332, the fingers 294, the hinges/springs associatedwith each finger 294, or any of the features of the lid 290 referencedabove, or any combination thereof, may be injection molded as a singlestructure. In another embodiment, some components of the lid 290 (e.g.,the bus bar interconnects 222) may be welded to the lid 290 (e.g., vialaser welding).

System and Method for Venting Pressurized Gas from a Battery Module

As shown in FIG. 43 , the lid 290 may include a venting assembly 297. Insome embodiments, the venting assembly 297 includes a vent chamber 298built into the lid 290. For example, the vent chamber 298 may be ahollowed out portion of the lid 290. FIG. 44 illustrates an embodimentof the vent chamber 298 that is located along a backbone section 340 ofthe lid 290. The lid 290 may include a vent chamber cover 338. To thatend, the vent chamber cover 338 may be disposed on the bottom of the lid290. The vent chamber cover 338 may include slots 342 configured todirect the gases vented from the battery cells 54 into the vent chamber298. Moreover, in some embodiments, the slots 342 are aligned with ventsin the battery cells 54. The vent chamber 298 acts as a conduit ormanifold for carrying vented gases from the battery cells 54 out of thebattery module 22. Since the vent chamber 298 is part of the lid 290,the vent chamber 298 may permit the placement of the PCB assembly 58just over the battery cells 54 and the lid 290. Thus, the vent chamber298 may be disposed between the battery cells 54 and the PCB assembly58. If one of the battery cells 54 encounters issues (e.g., overheating)that lead to a pressure build-up within the battery cell 54, the batterycell 54 may release the high pressure gases from a housing of thebattery cell 54 through the vent 312. The gases released from thebattery cell 54 may be vented out of the battery module 22 via the ventchamber 298, without flowing into and disrupting operation of thetemperature-sensitive equipment on the PCB 136 located just above thelid 290.

As shown in the illustrated embodiment, the vent chamber 298 may beconfigured to hold a vent guide 341 made from a relatively strongermaterial (e.g., steel) than the lid 290. FIG. 45 is a cutaway view ofthe vent guide 341 disposed in the vent chamber 298. As illustrated, thevent guide 341 may be open along a bottom portion 343 to receive thevented gases from the battery cells 54 and closed along a top portion345 to keep the gases from entering the PCB assembly 58 where they couldpotentially disrupt operation of the sensitive equipment thereon. Tothat end, the vent guide 341 may be substantially U-shaped (e.g., havinga substantially U-shaped cross section formed by the top portion 345 andtwo sidewalls 347 extending therefrom) in order to cover sidewalls 349and a top portion 351 of the vent chamber 298. In some embodiments, thesidewalls 347 of the vent guide 341 may extend past the sidewalls 349 ofthe vent chamber 298. Moreover, in some embodiments, the vent guide 341may not cover the entire vent chamber 298.

Because the vent guide 341 is disposed between the battery cells 54 andthe lid 290, the vent guide 341 may shield the vent chamber 298 fromdirect contact with the vented gases. Moreover, in embodiments where thevent guide 341 is made of metal, the vent guide 341 may absorb the heatof the vented gases to inhibit heating of the PCB assembly 58 disposedover the lid 290. For example, the vent guide 341 may include a U-shapedsteel plate, in some embodiments. As illustrated in FIG. 44 , the ventguide 341 may be a separate insert configured to slide into the ventchamber 298 of the lid 290. However, in other embodiments, the ventguide 341 may be integral with the lid 290. For example, in someembodiments, the vent guide 341 may be overmolded into the lid 290. As aresult, the vent guide 341 may be permanently disposed within the ventchamber 298.

In the illustrated embodiment, vent chamber cover 338 of the lid 290includes thirteen slots 342, one slot 342 corresponding to the vents 312on each of the battery cells. The slots 342 may facilitate a flow ofheated and pressurized gases from the vented battery cells 54 into thevent guide 341 within the vent chamber 298. The slots 342 may allow forvented gases to enter the vent guide 341 while functioning as astructural support of the lid 290, thus enabling the lid 290 to supportthe weight of itself and other components (e.g., PCB assembly 58) of thebattery module 22. It should be noted that the vent chamber 298 mayfunction as a stiffener for the lid 290, enabling the lid 290 to moreeffectively hold down the battery cells 54 located below the lid 290.The vent chamber 298 may help to maintain structural integrity of thelid 290, even against pressures exerted from the battery cells 54 duringa burst event. The vent guide 341 may provide further support wheninstalled.

In certain embodiments, the bottom surface of the vent chamber 298 maybe entirely open. For example, in embodiments where the stronger ventguide 341 is integral with the lid 290 (e.g., overmolded into the lid290), the slots 342 may be enlarged or eliminated altogether and theopen surface of the vent guide 341 used to capture the gases ventingfrom the battery cells 54. For example, the vent chamber 298 may be ahollowed out portion of the lid 290. Moreover, the hollowed out portionmay include a single opening (e.g., a single opening in the center, anopening extending the length of the vent chamber 298, etc.) configuredto receive vented gases from all of the plurality of battery cells. Theslots 342 may be any desirable shape and size that facilitates adequateventing of the battery cells 54 through the vent chamber 298 whileproviding a desired amount of structural support for the lid 290.

As illustrated, the vent chamber 298 may be generally tapered or wedgeshaped. More specifically, one end of the vent chamber 298 may includean opening 344 through which the vented gases may exit the vent chamber298 and/or the battery module 22. The vent chamber 298 may have itslargest cross sectional area at this end and gradually taper down to asmaller cross sectional area at the opposite end of the vent chamber298. More specifically, the vent chamber 298 may comprise a first enddisposed above one of the prismatic battery cells 54 proximate anopening or portal 344 (FIG. 46 ) and a second end disposed above anotherof the prismatic battery cells 54 that is farthest from the opening 344.The vent chamber 298 may be tapered such that a width of the ventchamber 298 is larger at the first end than a width of the vent chamber298 at the second end. The walls of the vent chamber 298 may taper alongone or both of directions aligned with the X axis 60 and the Z axis 64.The vent guide 341 may be similarly tapered. Tapered inner walls 346 ofthe vent chamber 298 are visible in the illustrated embodiment. Thetapered inner walls 346 may facilitate the access and removal of aninstallation tool used to insert the vent guide 341 into the ventchamber 298. In addition, holes 348 intermittently located along the topof the lid 290 may help the installation tool to remain alignedthroughout the installation process. In other embodiments, the ventchamber 298 may have a uniform cross section along its length or anyother desirable shape for facilitating installation of the vent guide341.

Once the gases released from the vent 312 of the battery cells 54 arepushed into the vent chamber 298, the vent chamber 298 and/or the ventguide 341 may act as a conduit to guide the pressurized gases away fromsensitive components of the battery module 22 and out of the batterymodule 22. FIGS. 46 and 47 diagrammatically represent two possibleembodiments of the battery module 22 that utilize the vent chamber 298to direct such gases out of the battery module 22. Specifically,pressurized gases may exit one or more battery cells 54 via the vents312 located at the top of the battery cells 54 and into the vent chamber298. The gases may flow through the vent chamber 298 (or the vent guide341 held within the vent chamber 298) toward the opening 344 of the ventchamber 298. This flow of gas is illustrated in both embodiments viaarrows 350.

In FIG. 46 , the opening 344 of the vent chamber 298 opens into a flowpath leading to an aperture 352 formed within the outside enclosure ofthe battery module 22. In the illustrated embodiment, the aperture 352is formed within the lower housing 50 of the battery module 22 and is insubstantially the same plane as the vent chamber 298. However, in otherembodiments, the aperture 352 may be disposed in the cover 52 of thebattery module 22. The vented gases may exit the battery module 22through the aperture 352 via a venting system 353, as illustrated byarrows 354. The venting system 353 may include the vent chamber 298, thevent guide 341, and the aperture 352. In some embodiments, the enclosuremay include numerous such apertures 352 (or other types of openingswithin the lower housing 50 and/or the cover 52) for removing thepressurized gases to the atmosphere. Moreover, the aperture 352 mayinclude a fitting and/or connector (e.g., threaded, barbed, etc.) tocouple the aperture 352 to a conduit for directing the vented gases toanother location. For example, the aperture 352 may have female threadsthat mate with male threads of a hose.

FIG. 47 illustrates an embodiment of the battery module 22 having achimney 356 built into the outer enclosure for releasing gas from thevent chamber 298 into the atmosphere. Upon exiting the opening 344 atthe end of the vent chamber 298, the vented gases may be routed towardthe chimney 356 and may exit through the chimney 356, via the ventingsystem 353, as shown by arrows 358. In some embodiments, the ventingsystem 353 may also include the chimney 356. In the illustratedembodiment, the chimney 356 is built into the cover 52 of the batterymodule 22, however, in other embodiments, the chimney 356 may form partof the lower housing 50. In still other embodiments, the battery module22 may include multiple such chimneys 356 formed within the lowerhousing 50 and/or the cover 52 for releasing the vented gases from thebattery module 22. Additionally, as mentioned above, the chimney 356 mayalso include fittings and/or connectors to mate with additionalcomponents of the vehicle.

It should be noted that any desirable combination of apertures 352 andchimneys 356 may be used in combination to vent the gases from the ventchamber 298 to an outside atmosphere. However, other types of openingsor fixtures may be built into the lower housing 50 or the cover 52 torelease the gases. In addition, the aperture 352 and/or the chimney 356of the above mentioned embodiments may be designed to mate with a hoseor other component of the vehicle. Such a hose may further direct thevented gases away from sensitive components located within the vehicle.

As described above, the apertures 352 and/or the chimney 356 may matewith additional hoses or components of the vehicle. FIG. 48 representsan embodiment of a fitting 360 coupled to the aperture 352 of theventing system 353. The fitting 360 may be screwed into the aperture 352in the lower housing 50. However, in other embodiments, the fitting 360may be connected in other ways. For example, the fitting 360 andaperture 352 may have quick connect fittings or the fitting 360 may bebolted to the lower housing 50. In still other embodiments, the fitting360 may be coupled to the cover 52 instead of the lower housing 50,depending on the location of the aperture 352 or chimney 356. Thefitting 360 may have an outlet 362 that mates with a hose or othervehicle component. As mentioned above, the outlet 362 may be threaded,barbed, or may include any other type of fitting or connector thatallows components to couple to one another. The fitting 360 may allowfor relatively simple removal of the battery module 22 from the vehiclecomponents (e.g., hoses), or vice versa. Moreover, the fitting 360 maybe oriented in a variety of directions (e.g., pointing downward,pointing upward, pointing to the side, etc.) to enable several optionswhen routing the vented gases away from the battery module 22 via ahose.

Layered Battery Module System and Method of Manufacture

To reduce the complexity of assembling the battery module 22, thecomponents of the battery module 22, described in detail above, may bearranged such that the battery module 22 is layered. As illustrated inthe exploded view of FIG. 49 , the components of the battery module 22may be layered on top of one another to assemble the battery module 22.In addition to easing the assembly of the battery module 22, layeringthe components of the battery module 22 in the illustrated manner mayresult in a more space-efficient design of the battery module 22 thanwould be available through conventional battery module arrangements.

FIG. 50 depicts a possible method 370 for assembling the battery module22 of FIG. 49 . As will be appreciated, some of the blocks representingsteps of the method 370 may be eliminated in certain embodiments, andother orders of the illustrated blocks may be employed in accordancewith present embodiments. The method 370 may include disposing theindividual battery cells 54 into the slots 70 of the lower housing 50 atblock 372. The battery cells 54 may be placed in the slots 70individually or simultaneously. In some embodiments, the placement maybe performed manually, while in other embodiments the placement may beperformed using pick-and-place machinery. The adapters 234 may then bepositioned on the aluminum post terminals of the battery cells 54 atblock 374. As mentioned above, the adapters 234 may be used inembodiments in which the post terminals of the battery cells 54 are madeof differing metals and the bus bar cell interconnects 222 are made fromonly one of the metals used for the post terminals. The adapters 234 mayfacilitate a transition between the pair of metals (e.g., copper toaluminum, or some other combination) used for the post terminals. Inother embodiments, as mentioned above, the bus bar cell interconnects222 may be links 260 that are made of both the metals used for the postterminals. In such embodiments, the links 260 facilitate transitionsbetween the pair of metals. As such the adapters 234 may not beutilized, thereby reducing the number of components to be assembledwithin the battery module 22.

Next, the lid assembly 56 may be assembled at block 376. Block 376 mayinclude, for example, installing the vent guide 341 into the ventchamber 298 of the lid 290 through the opening 344 at block 378. Asmentioned above, the vent guide 341 is configured to direct gases ventedfrom the battery cells 54 away from the PCB assembly 58. This insertionmay be performed manually or via an installation instrument used toslide and secure the vent guide 341 within the vent chamber 298. Incertain embodiments, the vent guide 341 may be integral with the lid 290and block 378 may not be performed, which may reduce the complexity ofassembling the lid assembly 56. Assembling the lid assembly 56 at block376 may also include mounting the bus bar cell interconnects 222 (e.g.,loops 224) onto the lid 290 at block 380. As noted above, the lid 290may include a number of posts, walls, engagement features, indentations,or other features that facilitate such placement and alignment of thebus bar cell interconnects 222 onto the lid 290. In addition, the busbar cell interconnects 222 and/or the mounting features on the lid 290may be configured such that the bus bar cell interconnects 222 will bereceived in a mounted orientation only when they are aligned properly.This “proper” alignment may be an alignment of individual bus bar cellinterconnects 222 relative to the lid 290 so that the bus bar cellinterconnects 222 are oriented to electrically couple the battery cells54 in a desired manner

The fully assembled lid assembly 56 may then be layered (i.e. disposed)onto the lower housing 50 and the battery cells 54 (with theircorresponding adapters 234) at block 382. As discussed above, the lowerhousing 50 may include attachment features that interface withcorresponding attachment features on the lid 290 to secure the lid 290with respect to the lower housing 50. For example, the lower housing 50may include clips 114 that interface with corresponding slots 302 of thelid 290. As will be appreciated, this mating arrangement may be reversedin other embodiments. Next, components 385 with upward facing bladeconnectors may be disposed onto the lid 290 at block 384. This mayinclude any components 385 of the battery module 22 that are configuredto be coupled to the PCB 136 from below, as well as components 385 thatare configured to extend through the PCB 136 from a position beneath thePCB 136. In the illustrated embodiment of FIG. 49 , for example, thesecomponents 385 may include the contactor 154 and the battery terminal 24coupled to its corresponding bladed portion 122 of connector 120. Thelid 290 may include indentations or recessed features for receivingthese components 385, such as the cavity 300 for receiving andsupporting the contactor 154. In other embodiments, the method 370 mayinclude disposing one or more of these components 385 in the lowerhousing 50 at a position beneath the lid 290. In such embodiments, thelid 290 may include openings through which the bladed components 385 mayextend upward for coupling to other components of the battery module 22.

After the components 385 with upward facing blade connectors aredisposed onto the lid 290 (and/or beneath the lid 290), the PCB 136 maybe disposed onto the lid assembly 56 at block 386. At this point, thePCB 136 may be equipped with the high current interconnects 140, thevoltage sense connection tabs 226, and the shunt 137 disposed thereon toform the PCB assembly 58. The voltage sense connection tabs 226 may bedisposed on the PCB 136 such that each of the overhanging tabs 226 isaligned with a contact surface of a corresponding loop 224 (or other busbar cell interconnect 222). Once properly aligned, the voltage senseconnection tabs 226 may be coupled to the loops 224 via laser welding,as discussed in further detail below. As noted above, the shunt 137 maybe disposed on and integral with the PCB 136, thereby reducing thecomplexity of assembling the PCB assembly 58. The high currentinterconnects 140 may be mounted to the PCB 136 such that they receivethe upward facing blade connectors within the downward facing openings145B of the high current interconnects 140, as described above. Inaddition, the high current interconnects 140 may be mounted on the PCB136 and soldered into contact with various traces disposed on or withinthe PCB 136, as described above.

Components 390 with downward facing blade connectors may be disposedonto the components of the PCB assembly 58 at block 388. Thesecomponents 390 may include any components that are configured to becoupled to the PCB 136 and/or to extend through the PCB 136 from aposition above the PCB 136. In the illustrated embodiment, thesecomponents 390 include the fuse assembly 153, the bus bars 155 and 138,and the battery terminal 26 coupled to its corresponding connector 121.The components 390 may each be aligned to interface with certaincomponents of the lower layers of the battery module 22. In particular,the components 390 with downward facing blade connectors may be insertedinto the upward facing openings 145A of the high current interconnects140, as described above. For instance, the bus bar 155 may be positionedsuch that one end is disposed in the upward facing opening 145A of oneof the high current interconnects 140 and the opposite end is layered ontop of one of the bus bar cell interconnects 222. The fuse assembly 153may be aligned such that each of the bladed fuse connectors 157extending downward from the fuse 156 are disposed in upward facingopenings 145A of two high current interconnects 140 disposed on the PCB136. The bus bar 138 may be positioned such that one end is in contactwith the shunt 137 and an opposite end is disposed over an end of one ofthe bus bar cell interconnects 222. Further, the battery terminal 26 andcorresponding connector 121 may be placed such that the bladed portion123 of the connector 121 rests atop the shunt 137.

In addition, certain connections between components within the batterymodule 22 may be formed by laser welding at block 392. As described indetail below, all of the components may be visible for welding fromabove. In embodiments employing the adapters 234, the welded connectionsmay be made between copper components. However, in other embodimentsemploying the links 260, the welded connections may be made betweenaluminum components. Finally, the cover 52 may be disposed over all ofthe internal components (e.g., PCB assembly 58, lid assembly 56, andbattery cells 54) of the battery module 22 at block 394. Specifically,the cover 52 may interface with the lower housing 50 to provide ahermetic seal of the battery module 22. As noted above, the lowerhousing 50 and the cover 52 may be equipped with mating features (e.g.,groove 116 and extension 117) to provide the desired seal. The cover 52and the lower housing 50 together may form a relatively robust containerand seal of the internal components of the battery module 22.

It should be noted that the above-described method 370 may enablerelatively efficient and simple assembly of the battery module 22. Inaddition, the layering of the battery module components may result in amore space efficient design than would be possible with otherarrangements. For example, the vent chamber 298 built into the lid 290enables the PCB 136 to be disposed directly above the battery cells 54,without concern of overheating of the board components in the event of aburst event in one of the battery cells 54. In another example,electrically coupling high current components to one another and to thePCB 136 via the high interconnects 140 may be done without cabling,fasteners, and other means traditionally used to make electrical andmechanical connections between high current components and a PCB.Furthermore, it should be noted that each of the various subassemblies(e.g., lower housing 50, battery cells 54, lid assembly 56, PCB assembly58) may be fully assembled and then simply layered one on top of theother before any additional electrical connections (e.g., welding) aremade.

Layered Printed Circuit Board for Improved Signal Protection

In addition to the large scale layering of subassemblies to form thebattery module 22, smaller scale layering may be used to form the PCB136 in a way that allows the PCB 136 to be layered within the batterymodule 22 as described above. In conventional multi-layered PCBs, theindividual layers of the PCB are arranged such that the circuitry isexposed on the outer layers of the PCB. In vehicle battery contexts,this can expose the circuitry to exposed to electromagnetic interferencewhen placed in close proximity to other electrical components. Inparticular, insulating layers within multi-layered PCBs may form theinternal layers, while some or all of the circuitry, trace, andelectronic components may be disposed on the external layers of themulti-layered PCB. As a result, such multi-layered PCBs will often bedisposed in an electromagnetic compatibility (EMC) shield, such as ametal housing or cage. However, such shielding options increase thespace requirements for any battery module or system that contains aconventional multi-layered PCB.

To reduce the risk of electromagnetic interference without necessitatingan external shield, the layers of the presently disclosed PCB 136 may bearranged as depicted in FIG. 51 . As will be discussed further below,the layers of the PCB 136 may be arranged such that the layerscontaining circuitry, traces, and electronic components are the internallayers, such that the external layers shield the circuitry, traces, andelectronic components. As such, the PCB 136 may still be manufacturedusing conventional PCB manufacturing techniques. Further, by foregoingthe external shields, the PCB 136 may have a more space-efficient designthan conventional PCBs, which may prove particularly advantageous forthe layered battery module 22 described above.

As depicted in FIG. 51 , the PCB 136 may include several signal layers396 and two external ground cage layers 398. All of the signal layers396 may be disposed between the ground cage layers 398. The signallayers 396 may include a distributed power layer 400, a distributedground layer 402, and inner signal layers 404. All circuit signals maybe routed on the inner signal layers 404 of the PCB 136. The powercomponents and ground components of the circuitry present in the PCB 136may be distributed across the outer surfaces of the inner signal layers404 and electrically coupled to the distributed power layer 400 and thedistributed ground layer 402 as necessary. Further, circuit ground loopsmay be constrained within the circuit in relatively small areas (e.g.,electrically coupled to the distributed ground layer 402) along theinner signal layers 404.

The ground cage layers 398 may be made of a conductive material, and mayform complete ground shields on both the top and bottom surfaces of thePCB 136. In certain embodiments, the ground cage layers 398 may includea thin layer of insulative material disposed on top of the conductivematerial. As such, the ground cage layers 398 may shield the internalcircuitry of the PCB 136 from battery and vehicle noise. Morespecifically, the ground cage layers 398 may provide EMI protection ofthe battery electronics, which may need to measure very small signalswith a high degree of accuracy. As mentioned above, instead of beingdisposed on the external layers of the PCB 136, all of the signal tracesmay be embedded within the PCB 136 on the inner signal layers 404. Theexternal ground cage layers 398 may provide protection for the internalcircuitry of the PCB 136 from high currents present in the bus bar cellinterconnects 22 and the battery cells 54 located directly beneath thePCB 136. The ground cage layers 398 may also provide protection for theinternal circuitry of the PCB 136 from electrical noise coming from thevehicle 10 outside of the battery module 22. In this way, the groundcage layers 398 may provide a level of protection that would not beavailable to a traditional PCB having electronic components and signaltraces disposed on one or both external layers.

Because the ground cage layers 398 form a ground shield on both the topand bottom of the PCB 136, the PCB 136 does not have to employ EMIshielding options such as metal housings or cages. Indeed, theillustrated arrangement may allow the PCB 136 to be functional withinthe intended electromagnetic environment of the battery module 22without experiencing undesirable functional issues or degradation due toomitting an external shield. For example, this particular arrangement ofthe PCB 136 may allow for the PCB to be placed in close proximity to thebus bars 155 and the battery cells 54 without being encased in aseparate housing, thereby reducing the space requirements for thebattery module 22. The robust layered design of the PCB 136 may work inconjunction with the other layered elements of the battery module 22 toreduce the overall size of the battery module 22.

As will be appreciated, a similar PCB layout may be used within aseparate battery management system (BMS) to perform control andmonitoring operations of the battery system 20. Such embodiments mayinclude simply the illustrated PCB 136 enclosed in a simple plastichousing, as opposed to a larger metallic container.

Method for Establishing Connections Between Internal Battery Components

As mentioned above with respect to the method 370, several componentswithin the battery module 22 may be connected through laser welds. FIG.52 is a top view of the battery module 22 without the cover 52,illustrating each of a set of welded connections (e.g., at weldingpoints) that may be made during the assembly process. It should be notedthat some of the welded connections and components discussed below(e.g., the adapters 234) may not be visible from the top viewillustrated in FIG. 52 , but these components are discussed withreference to FIG. 34 .

The set of welded connections that may be made during assembly of thebattery module 22 includes a number of different welding points. Forexample, all of the welding points relating to the bus bar cellinterconnects 222 may be accessible from above the interconnect assembly220. More specifically, the welding points for all of the welds betweenthe copper terminals 230 of the battery cells 54 and the correspondingbus bar cell interconnects 222 may be accessible from above the batterycells 54 (e.g., welds 410). This may be the case in embodiments wereeach battery cell 54 has one copper terminal 230 and one aluminumterminal 232, as illustrated, as well as in embodiments where bothterminals of each battery cell 54 are copper. In battery modules 22 thatutilize the adapter 234 to transition between materials, all of thewelding points for the welds between copper portions (e.g., ends 238) ofthe adapters 234 and the corresponding bus bar cell interconnects 222may be accessible from above the battery cells 54. Further, all of thewelding points for all of the welds between the voltage sense connectiontabs 226 of the PCB 136 and the corresponding bus bar cell interconnects222 may be accessible from above the battery cells 54 (e.g., welds 412).In some embodiments, the bus bar cell interconnects 22 may bespecifically shaped (e.g., as loops 224) to make all of these weldingpoints accessible from above.

Copper-to-copper welds made from above the battery cells 54 may also beused to join various other sets of welded components within the batterymodule 22. For example, all of the welding points for all of the weldsbetween the shunt 137 of the PCB 136 and a first bus bar (e.g., the busbar 138), between the shunt 137 and the bladed connector 121 (e.g., thebladed portion 123 of the bladed connector 121) of the battery module22, or both, may be accessible from above the battery cells 54 (e.g.,welds 416). Further, the welding point for the weld between the firstbus bar 138 and either a corresponding copper terminal 230 of one of thebattery cells 54 or a copper portion (e.g., the end 238) of acorresponding adapter 234 may be accessible from above the battery cells54 (e.g., weld 414). Further, the welding point for the weld between asecond bus bar (e.g., the second bus bar 155 coupled to the high currentinterconnect 140) of the battery module 22 and either the correspondingcopper terminal 230 of one of the battery cells 54 or a copper portion(e.g., the end 238) of a corresponding adapter 234 may be accessiblefrom above the battery cells 54 (e.g., weld 415). As discussed above, insome embodiments, the bladed terminal connector 121 may include thebladed portion 123, where the bladed portion 123 is integral (e.g., apart of a single structure) with the connector 121. However, in otherembodiments, the bladed portion 123 may be a separate component from theconnector 121. As such, the bladed portion 123 may be welded at awelding point to the connector 121, where the welding point isaccessible from above the battery cells 54 (e.g., weld 417), and thebladed portion 123 may be welded to the shunt 137, as described above.Accordingly, the bladed portion 123 is welded to both the shunt 137 andthe connector 121, such that the bladed portion 123 and the connector121 together provide electrical communication between the shunt 137 andthe terminal 26.

The illustrated components or sets of components may each be properlyplaced and aligned relative to each other, as discussed above. When thevarious connections between these components are made, the associatedwelding may be performed directly from above, as each welded connectionis in full view from this perspective. Each of the components may belaser welded, and, in some embodiments, all of the welds may be betweencopper components or at least between components of the same material.This may streamline the manufacturing process, as the welds may each beformed via the same laser welding machine operating within a singlesetting.

In the illustrated embodiment, the bus bar interconnects 222 (e.g.,loops 224) may be welded to the copper terminals 230 of the batterycells 54 via the welds 410 at one end (e.g., terminal mating end 242) ofthe bus bar interconnects 222. In addition, the voltage sense connectiontabs 226, the bus bar interconnects 222, and the copper portion of theadapters 234 (e.g., as shown in FIG. 34 ) may be welded together via thewelds 412 at the opposite end (e.g., plate contact end 240 (e.g., asshown in FIG. 34 )) of the bus bar interconnects 222. As discussedabove, these voltage sense connection tabs 226 may be initially coupledto the PCB 136 prior to placement of the PCB 136 onto the lid assembly56. In addition to the above mentioned welded connections, the bus bars138 and 155 may each be welded to a copper portion of an adjacent copperbattery cell terminal 230 or a copper portion of the adapter 234disposed on an adjacent aluminum battery cell terminal 232. Such welds414 between these components may establish the connections between thebattery cells 54 and the various high current components within thebattery module 22. Further, the bus bar 138 and the bladed portion 123may each be coupled to the shunt 137 via welds 416, in order tofacilitate providing the power output from the battery cells 54 throughthe shunt 137 and into the bladed portion 123 of the battery terminal26. At the other end of the battery module 22, the power output from thebattery cells 54 may reach the opposing battery terminal 24 through theconnected bus bar 155, the contactor 154, the fuse assembly 153, and thebladed portion 122.

In the illustrated embodiment, all of the high current connections madewithin the battery module 22 are either established via laser weldingthe components together (e.g., between the various bus bars,interconnects, voltage sense components, battery terminals, and terminalposts) or via the high current interconnects 140 (e.g., between thecontactor, fuse assembly, bus bars, terminal posts, and on-boardcomponents of the PCB). This may facilitate a relatively efficientassembly method, especially when applied with the layering techniquedescribed above with reference to FIGS. 49 and 50 . As noted above, theassembly may be configured such that all of the welds (e.g., the welds410, 412, 414, 415, 416, and 417) are copper-to-copper welds.Additionally, the assembly may be configured such that welding points ofall of the welds (e.g., points where the welds 410, 412, 414, 415, 416and 417 are to be made) may be aligned such that a welding tool canaccess all of the welding points from above the battery cells 54.Further, all, most, or some of the welding points may be aligned on asubstantially even level above the battery cells 54 such that thewelding tool can access all of the welding points in a substantiallylevel plane. However, it should be noted that other methods may existfor assembling the various embodiments of the battery module 22disclosed herein.

While only certain features and embodiments of the disclosure have beenillustrated and described, many modifications and changes may occur tothose skilled in the art (e.g., variations in sizes, dimensions,structures, shapes and proportions of the various elements, values ofparameters (e.g., temperatures, pressures, etc.), mounting arrangements,use of materials, colors, orientations, etc.) without materiallydeparting from the novel teachings and advantages of the subject matterrecited in the claims. The order or sequence of any process or methodsteps may be varied or re-sequenced according to alternativeembodiments. It is, therefore, to be understood that the appended claimsare intended to cover all such modifications and changes as fall withinthe true spirit of the disclosed embodiments. Furthermore, in an effortto provide a concise description of the exemplary embodiments, allfeatures of an actual implementation may not have been described. Itshould be appreciated that in the development of any such actualimplementation, as in any engineering or design project, numerousimplementation specific decisions may be made. Such a development effortmight be complex and time consuming, but would nevertheless be a routineundertaking of design, fabrication, and manufacture for those ofordinary skill having the benefit of this disclosure, without undueexperimentation.

1. A bus bar, comprising: a first end including a first material andconfigured to be coupled to a terminal of a first battery cell of abattery module; a first collar disposed on the first end and includingthe first material, the first collar being configured to receive andsurround the terminal of the first battery cell of the battery module; asecond end including a second material and configured to be coupled to aterminal of a second battery cell of the battery module, the first andsecond battery cells of the battery module being adjacent to oneanother; a second collar disposed on the second end and including thesecond material, the second collar being configured to receive andsurround the terminal of the second battery cell of the battery module;and a joint electrically and mechanically coupling the first end and thesecond end, the joint providing a gas tight seal between the first endand the second end.
 2. The bus bar of claim 1, wherein the firstmaterial includes copper, and the second material includes aluminum. 3.The bus bar of claim 1, wherein the first collar and the second collarare disposed on a lower surface of the bus bar when the bus bar iscoupled to the terminals of the first and second battery cells, andwherein the first collar and the second collar extend in a directionsubstantially perpendicular to a plane of the lower surface of the busbar.
 4. The bus bar of claim 3, wherein the first collar and the secondcollar each include an inner circumference configured to receive andsurround one of the terminals of the first and second battery cells andan outer circumference, wherein the inner and outer circumferences aresubstantially constant along the direction.
 5. The bus bar of claim 4,wherein the bus bar comprises an indication formed in the first end ofthe bus bar configured to differentiate the first end from the secondend.
 6. The bus bar of claim 5, wherein the first collar surrounds anaperture in the first end of the bus bar and the second collar surroundsan aperture in the second end of the bus bar.
 7. The bus bar of claim 1,further comprising a busbar curved portion, the busbar curved portionbeing concave.
 8. The bus bar of claim 7, the busbar curved portioncomprising a first curved portion and a second curved portion, the firstcurved portion sloping from the joint toward the terminal of the firstbattery cell, the second curved portion sloping from the joint towardthe terminal of the second battery cell.
 9. The bus bar of claim 8, thefirst curved portion ending on collar outer circumference of theterminal of the first battery cell, and the second curved portion endingon a collar outer circumference of the terminal of the second batterycell.
 10. A method of manufacturing a bus bar, the method comprising:forming a first end of the bus bar from at least a first material, thefirst end being configured to be coupled to a terminal of a firstbattery cell of a batter module; disposing a first collar on the firstend, the first collar including the first material, the first collarbeing configured to receive and surround the terminal of the firstbattery cell of the battery module; forming a second end of the bus barfrom at least a second material, the second end being configured to becoupled to a terminal of a second battery cell of the battery module,the first and second battery cells of the battery module being adjacentto one another; disposing a second collar on the second end, the secondcollar including the second material, the second collar being configuredto receive and surround the terminal of the second battery cell of thebattery module; and electrically and mechanically coupling a joint tothe first end and the second end, the joint providing a gas tight sealbetween the first end and the second end.
 11. The method of claim 10,wherein the first material includes copper, and the second materialincludes aluminum.
 12. The method of claim 10, further comprisingdisposing the first collar and the second collar on a lower surface ofthe bus bar when the bus bar is coupled to the terminals of the firstand second battery cells, the first collar and the second collarextending in a direction substantially perpendicular to a plane of thelower surface of the bus bar.
 13. The method of claim 12, wherein thefirst collar and the second collar each include an inner circumferenceconfigured to receive and surround one of the terminals of the first andsecond battery cells and an outer circumference, wherein the inner andouter circumferences are substantially constant along the direction. 14.The method of claim 13, wherein forming the first end comprises formingan indication in the first end of the bus bar, the indication beingconfigured to differentiate the first end from the second end.
 15. Themethod of claim 14, further comprising surrounding an aperture in thefirst end of the bus bar with the first collar, and surrounding anaperture in the second end of the bus bar with the second collar. 16.The method of claim 10, further comprising forming a busbar curvedportion, the busbar curved portion being concave.
 17. The method ofclaim 16, wherein forming the busbar curved portion includes forming afirst curved portion and a second curved portion, the first curvedportion sloping from the joint toward the terminal of the first batterycell, the second curved portion sloping from the joint toward theterminal of the second battery cell.
 18. The method of claim 17, whereinthe first curved portion ends on collar outer circumference of theterminal of the first battery cell, and the second curved portion endson a collar outer circumference of the terminal of the second batterycell.
 19. A bus bar, comprising: a first end including a first materialand configured to be coupled to a terminal of a first battery cell of abattery module; a first collar disposed on the first end and includingthe first material, the first collar being configured to receive andsurround the terminal of the first battery cell of the battery module; asecond end including a second material and configured to be coupled to aterminal of a second battery cell of the battery module, the first andsecond battery cells of the battery module being adjacent to oneanother; a second collar disposed on the second end and including thesecond material, the second collar being configured to receive andsurround the terminal of the second battery cell of the battery module;the first collar and the second collar being disposed on a lower surfaceof the bus bar when the bus bar is coupled to the terminals of the firstand second battery cells, and wherein the first collar and the secondcollar extend in a direction substantially perpendicular to a plane ofthe lower surface of the bus bar; a joint electrically and mechanicallycoupling the first end and the second end, the joint providing a gastight seal between the first end and the second end; and a busbar curvedportion, the busbar curved portion being concave.
 20. The bus bar ofclaim 19, the curved portion comprising a first curved portion and asecond curved portion, the first curved portion sloping from the jointtoward the terminal of the first battery cell, the second curved portionsloping from the joint toward the terminal of the second battery cell;and the first curved portion ending on collar outer circumference of theterminal of the first battery cell, and the second curved portion endingon a collar outer circumference of the terminal of the second batterycell.